Method and apparatus of handling device-to-device resource pool without physical sidelink feedback channel in a wireless communication system

ABSTRACT

A method and apparatus are disclosed from the perspective of a first device. In one embodiment, the method includes the first device receiving a configuration, from a network node, of a first sidelink resource pool without any Physical Sidelink Feedback Channel (PSFCH) resource. The method further includes the first device receiving a first sidelink grant transmitted, configured, or scheduled by the network node, wherein the first sidelink grant schedules or indicates at least a first sidelink resource in the first sidelink resource pool. Furthermore, the method includes the first device expecting or considering that the first sidelink grant provides no Physical Uplink Control Channel (PUCCH) resource for reporting Sidelink (SL) Hybrid Automatic Repeat Request (HARQ) feedback.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present Application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/942,937 filed on Dec. 3, 2019, the entiredisclosure of which is incorporated herein in their entirety byreference.

FIELD

This disclosure generally relates to wireless communication networks,and more particularly, to a method and apparatus of handlingdevice-to-device resource pool without physical sidelink feedbackchannel in a wireless communication system.

BACKGROUND

With the rapid rise in demand for communication of large amounts of datato and from mobile communication devices, traditional mobile voicecommunication networks are evolving into networks that communicate withInternet Protocol (IP) data packets. Such IP data packet communicationcan provide users of mobile communication devices with voice over IP,multimedia, multicast and on-demand communication services.

An exemplary network structure is an Evolved Universal Terrestrial RadioAccess Network (E-UTRAN). The E-UTRAN system can provide high datathroughput in order to realize the above-noted voice over IP andmultimedia services. A new radio technology for the next generation(e.g., 5G) is currently being discussed by the 3GPP standardsorganization. Accordingly, changes to the current body of 3GPP standardare currently being submitted and considered to evolve and finalize the3GPP standard.

SUMMARY

A method and apparatus are disclosed from the perspective of a firstdevice. In one embodiment, the method includes the first devicereceiving a configuration, from a network node, of a first sidelinkresource pool without any Physical Sidelink Feedback Channel (PSFCH)resource. The method further includes the first device receiving a firstsidelink grant transmitted, configured, or scheduled by the networknode, wherein the first sidelink grant schedules or indicates at least afirst sidelink resource in the first sidelink resource pool.Furthermore, the method includes the first device expecting orconsidering that the first sidelink grant provides no Physical UplinkControl Channel (PUCCH) resource for reporting Sidelink (SL) HybridAutomatic Repeat Request (HARQ) feedback.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram of a wireless communication system according toone exemplary embodiment.

FIG. 2 is a block diagram of a transmitter system (also known as accessnetwork) and a receiver system (also known as user equipment or UE)according to one exemplary embodiment.

FIG. 3 is a functional block diagram of a communication system accordingto one exemplary embodiment.

FIG. 4 is a functional block diagram of the program code of FIG. 3according to one exemplary embodiment.

FIG. 5 is a reproduction of Table 14.2-1 of 3GPP TS 36.213 V15.4.0.

FIG. 6 is a reproduction of Table 14.2-2 of 3GPP TS 36.213 V15.4.0.

FIG. 7 is a reproduction of Table 14.2.1-1 of 3GPP TS 36.213 V15.4.0.

FIG. 8 is a reproduction of Table 14.2.1-2 of 3GPP TS 36.213 V15.4.0.

FIG. 9 is a flow chart according to one exemplary embodiment.

FIG. 10 is a flow chart according to one exemplary embodiment.

FIG. 11 is a flow chart according to one exemplary embodiment.

DETAILED DESCRIPTION

The exemplary wireless communication systems and devices described belowemploy a wireless communication system, supporting a broadcast service.Wireless communication systems are widely deployed to provide varioustypes of communication such as voice, data, and so on. These systems maybe based on code division multiple access (CDMA), time division multipleaccess (TDMA), orthogonal frequency division multiple access (OFDMA),3GPP LTE (Long Term Evolution) wireless access, 3GPP LTE-A orLTE-Advanced (Long Term Evolution Advanced), 3GPP2 UMB (Ultra MobileBroadband), WiMax, 3GPP NR (New Radio), or some other modulationtechniques.

In particular, the exemplary wireless communication systems devicesdescribed below may be designed to support one or more standards such asthe standard offered by a consortium named “3rd Generation PartnershipProject” referred to herein as 3GPP, including: TS 36.213 V15.4.0(2018-12), “E-UTRA; Physical layer procedures (Release 15)”; TS 36.212V15.4.0 (2018-12), “E-UTRA); Physical layer; Multiplexing and channelcoding (Release 15)”; TS 36.211 V15.4.0 (2018-12), “E-UTRA); Physicallayer; Physical channels and modulation (Release 15)”; RP-191723,“Revised WID on 5G V2X with NR sidelink”, LG Electronics; R1-1810051,“Final Report of 3GPP TSG RAN WG1 #94 v1.0.0 (Gothenburg, Sweden,20th-24th Aug. 2018)”; R1-1812101, “Final Report of 3GPP TSG RAN WG1#94bis v1.0.0 (Chengdu, China, 8th-12h Oct. 2018)”; R1-1901482, “FinalReport of 3GPP TSG RAN WG1 #95 v0.1.0 (Spokane, USA, 12th-16h Nov.2018)”; R1-1901483, “Final Report of 3GPP TSG RAN WG1 #AH_1901 v1.0.0(Taipei, Taiwan, 21st-25th Jan. 2019)”; R1-1905837, “Final Report of3GPP TSG RAN WG1 #96 v2.0.0 (Athens, Greece, 25th Feb.-1st Mar. 2019)”;R1-1905921, “Final Report of 3GPP TSG RAN WG1 #96bis v1.0.0 (Xi'an,China, 8th-12th Apr. 2019)”; R1-1907973, “Final Report of 3GPP TSG RANWG1 #97 v1.0.0 (Reno, USA, 13th-17th May 2019)”; R1-1909942, “FinalReport of 3GPP TSG RAN WG1 #98 v1.0.0 (Prague, Czech Rep, 26th-30th Aug.2019)”; R1-1913275, “Final Report of 3GPP TSG RAN WG1 #98bis v2.0.0(Chongqing, China, 14th-20th Oct. 2019)”; Draft Report of 3GPP TSG RANWG1 #99 (Reno, USA, 18th-22nd Nov. 2019). The standards and documentslisted above are hereby expressly incorporated by reference in theirentirety.

FIG. 1 shows a multiple access wireless communication system accordingto one embodiment of the invention. An access network 100 (AN) includesmultiple antenna groups, one including 104 and 106, another including108 and 110, and an additional including 112 and 114. In FIG. 1, onlytwo antennas are shown for each antenna group, however, more or fewerantennas may be utilized for each antenna group. Access terminal 116(AT) is in communication with antennas 112 and 114, where antennas 112and 114 transmit information to access terminal 116 over forward link120 and receive information from access terminal 116 over reverse link118. Access terminal (AT) 122 is in communication with antennas 106 and108, where antennas 106 and 108 transmit information to access terminal(AT) 122 over forward link 126 and receive information from accessterminal (AT) 122 over reverse link 124. In a FDD system, communicationlinks 118, 120, 124 and 126 may use different frequency forcommunication. For example, forward link 120 may use a differentfrequency then that used by reverse link 118.

Each group of antennas and/or the area in which they are designed tocommunicate is often referred to as a sector of the access network. Inthe embodiment, antenna groups each are designed to communicate toaccess terminals in a sector of the areas covered by access network 100.

In communication over forward links 120 and 126, the transmittingantennas of access network 100 may utilize beamforming in order toimprove the signal-to-noise ratio of forward links for the differentaccess terminals 116 and 122. Also, an access network using beamformingto transmit to access terminals scattered randomly through its coveragecauses less interference to access terminals in neighboring cells thanan access network transmitting through a single antenna to all itsaccess terminals.

An access network (AN) may be a fixed station or base station used forcommunicating with the terminals and may also be referred to as anaccess point, a Node B, a base station, an enhanced base station, anevolved Node B (eNB), or some other terminology. An access terminal (AT)may also be called user equipment (UE), a wireless communication device,terminal, access terminal or some other terminology.

FIG. 2 is a simplified block diagram of an embodiment of a transmittersystem 210 (also known as the access network) and a receiver system 250(also known as access terminal (AT) or user equipment (UE)) in a MIMOsystem 200. At the transmitter system 210, traffic data for a number ofdata streams is provided from a data source 212 to a transmit (TX) dataprocessor 214.

In one embodiment, each data stream is transmitted over a respectivetransmit antenna. TX data processor 214 formats, codes, and interleavesthe traffic data for each data stream based on a particular codingscheme selected for that data stream to provide coded data.

The coded data for each data stream may be multiplexed with pilot datausing OFDM techniques. The pilot data is typically a known data patternthat is processed in a known manner and may be used at the receiversystem to estimate the channel response. The multiplexed pilot and codeddata for each data stream is then modulated (i.e., symbol mapped) basedon a particular modulation scheme (e.g., BPSK, QPSK, M-PSK, or M-QAM)selected for that data stream to provide modulation symbols. The datarate, coding, and modulation for each data stream may be determined byinstructions performed by processor 230.

The modulation symbols for all data streams are then provided to a TXMIMO processor 220, which may further process the modulation symbols(e.g., for OFDM). TX MIMO processor 220 then provides N_(T) modulationsymbol streams to N_(T) transmitters (TMTR) 222 a through 222 t. Incertain embodiments, TX MIMO processor 220 applies beamforming weightsto the symbols of the data streams and to the antenna from which thesymbol is being transmitted.

Each transmitter 222 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel. N_(T)modulated signals from transmitters 222 a through 222 t are thentransmitted from N_(T) antennas 224 a through 224 t, respectively.

At receiver system 250, the transmitted modulated signals are receivedby N_(R) antennas 252 a through 252 r and the received signal from eachantenna 252 is provided to a respective receiver (RCVR) 254 a through254 r. Each receiver 254 conditions (e.g., filters, amplifies, anddownconverts) a respective received signal, digitizes the conditionedsignal to provide samples, and further processes the samples to providea corresponding “received” symbol stream.

An RX data processor 260 then receives and processes the N_(R) receivedsymbol streams from N_(R) receivers 254 based on a particular receiverprocessing technique to provide N_(T) “detected” symbol streams. The RXdata processor 260 then demodulates, deinterleaves, and decodes eachdetected symbol stream to recover the traffic data for the data stream.The processing by RX data processor 260 is complementary to thatperformed by TX MIMO processor 220 and TX data processor 214 attransmitter system 210.

A processor 270 periodically determines which pre-coding matrix to use(discussed below). Processor 270 formulates a reverse link messagecomprising a matrix index portion and a rank value portion.

The reverse link message may comprise various types of informationregarding the communication link and/or the received data stream. Thereverse link message is then processed by a TX data processor 238, whichalso receives traffic data for a number of data streams from a datasource 236, modulated by a modulator 280, conditioned by transmitters254 a through 254 r, and transmitted back to transmitter system 210.

At transmitter system 210, the modulated signals from receiver system250 are received by antennas 224, conditioned by receivers 222,demodulated by a demodulator 240, and processed by a RX data processor242 to extract the reserve link message transmitted by the receiversystem 250. Processor 230 then determines which pre-coding matrix to usefor determining the beamforming weights then processes the extractedmessage.

Turning to FIG. 3, this figure shows an alternative simplifiedfunctional block diagram of a communication device according to oneembodiment of the invention. As shown in FIG. 3, the communicationdevice 300 in a wireless communication system can be utilized forrealizing the UEs (or ATs) 116 and 122 in FIG. 1 or the base station (orAN) 100 in FIG. 1, and the wireless communications system is preferablythe NR system. The communication device 300 may include an input device302, an output device 304, a control circuit 306, a central processingunit (CPU) 308, a memory 310, a program code 312, and a transceiver 314.The control circuit 306 executes the program code 312 in the memory 310through the CPU 308, thereby controlling an operation of thecommunications device 300. The communications device 300 can receivesignals input by a user through the input device 302, such as a keyboardor keypad, and can output images and sounds through the output device304, such as a monitor or speakers. The transceiver 314 is used toreceive and transmit wireless signals, delivering received signals tothe control circuit 306, and outputting signals generated by the controlcircuit 306 wirelessly. The communication device 300 in a wirelesscommunication system can also be utilized for realizing the AN 100 inFIG. 1.

FIG. 4 is a simplified block diagram of the program code 312 shown inFIG. 3 in accordance with one embodiment of the invention. In thisembodiment, the program code 312 includes an application layer 400, aLayer 3 portion 402, and a Layer 2 portion 404, and is coupled to aLayer 1 portion 406. The Layer 3 portion 402 generally performs radioresource control. The Layer 2 portion 404 generally performs linkcontrol. The Layer 1 portion 406 generally performs physicalconnections.

3GPP TS 36.213 specifies the UE procedure for V2X transmission inLTE/LTE-A. The V2X transmissions are performed as sidelink transmissionmode 3 or sidelink transmission mode 4 as follows:

14 UE Procedures Related to Sidelink

A UE can be configured by higher layers with one or more PSSCH resourceconfiguration(s). A PSSCH resource configuration can be for reception ofPSSCH, or for transmission of PSSCH. The physical sidelink sharedchannel related procedures are described in Subclause 14.1.

A UE can be configured by higher layers with one or more PSCCH resourceconfiguration(s). A PSCCH resource configuration can be for reception ofPSCCH, or for transmission of PSCCH and the PSCCH resource configurationis associated with either sidelink transmission mode 1,2,3 or sidelinktransmission mode 4. The physical sidelink control channel relatedprocedures are described in Subclause 14.2.

[ . . . ]

14.1 Physical Sidelink Shared Channel Related Procedures

14.1.1 UE Procedure for Transmitting the PSSCH

[ . . . ]

If the UE transmits SCI format 1 on PSCCH according to a PSCCH resourceconfiguration in subframe n, then for the corresponding PSSCHtransmissions of one TB

-   -   for sidelink transmission mode 3,        -   the set of subframes and the set of resource blocks are            determined using the subframe pool indicated by the PSSCH            resource configuration (described in Subclause 14.1.5) and            using “Retransmission index and Time gap between initial            transmission and retransmission” field and “Frequency            resource location of the initial transmission and            retransmission” field in the SCI format 1 as described in            Subclause 14.1.1.4A.    -   for sidelink transmission mode 4,        -   the set of subframes and the set of resource blocks are            determined using the subframe pool indicated by the PSSCH            resource configuration (described in Subclause 14.1.5) and            using “Retransmission index and Time gap between initial            transmission and retransmission” field and “Frequency            resource location of the initial transmission and            retransmission” field in the SCI format 1 as described in            Subclause 14.1.1.4B.            [ . . . ]            14.1.1.6 U E Procedure for Determining the Subset of            Resources to be Reported to Higher Layers in PSSCH Resource            Selection in Sidelink Transmission Mode 4 and in Sensing            Measurement in Sidelink Transmission Mode 3

In sidelink transmission mode 4, when requested by higher layers insubframe n for a carrier, the UE shall determine the set of resources tobe reported to higher layers for PSSCH transmission according to thesteps described in this Subclause. Parameters L_(subCH) the number ofsub-channels to be used for the PSSCH transmission in a subframe,P_(rsvp_TX) the resource reservation interval, and prio_(TX) thepriority to be transmitted in the associated SCI format 1 by the UE areall provided by higher layers (described in [8]). C_(resel) isdetermined according to Subclause 14.1.1.4B.

In sidelink transmission mode 3, when requested by higher layers insubframe n for a carrier, the UE shall determine the set of resources tobe reported to higher layers in sensing measurement according to thesteps described in this Subclause. Parameters L_(subCH), P_(rsvp_TX) andprio_(TX) are all provided by higher layers (described in [11]).C_(resel) is determined by C_(resel)=10*SL_RESOURCE_RESELECTION_COUNTER,where SL_RESOURCE_RESELECTION_COUNTER is provided by higher layers [11].

If partial sensing is not configured by higher layers then the followingsteps are used:

-   -   1) A candidate single-subframe resource for PSSCH transmission        R_(x,y) is defined as a set of L_(subCH) contiguous sub-channels        with sub-channel x+j in subframe t_(y) ^(SL) where j=0, . . . ,        L_(subCH)−1. The UE shall assume that any set of L_(subCH)        contiguous sub-channels included in the corresponding PSSCH        resource pool (described in 14.1.5) within the time interval        [n+T₁, n+T₂] corresponds to one candidate single-subframe        resource, where selections of T₁ and T₂ are up to UE        implementations under T₁≤4 and T_(2min) (prio_(TX))≤T₂≤100, if        T_(2min)(prio_(TX)) is provided by higher layers for prio_(TX),        otherwise 20≤T₂≤100. UE selection of T₂ shall fulfil the latency        requirement. The total number of the candidate single-subframe        resources is denoted by M_(total).    -   2) The UE shall monitor subframes t_(n′−10×P) _(step) ^(SL),        t_(n′−10×P) _(step+1) ^(SL), . . . , t_(n′−1) ^(SL) except for        those in which its transmissions occur, where t_(n′) ^(SL)=n if        subframe n belongs to the set (t₀ ^(SL), t₁ ^(SL), . . . , t_(T)        _(max) ^(SL)), otherwise subframe t_(n′) ^(SL) is the first        subframe after subframe n belonging to the set (t₀ ^(SL), t₁        ^(SL), . . . , t_(T) _(max) ^(SL)). The UE shall perform the        behaviour in the following steps based on PSCCH decoded and        S-RSSI measured in these subframes.    -   3) The parameter Th_(a,b) is set to the value indicated by the        i-th SL-ThresPSSCH-RSRP field in SL-ThresPSSCH-RSRP-List where        i=a*8+b+1.    -   4) The set S_(A) is initialized to the union of all the        candidate single-subframe resources. The set S_(B) is        initialized to an empty set.    -   5) The UE shall exclude any candidate single-subframe resource        R_(x,y) from the set S_(A) if it meets all the following        conditions:        -   the UE has not monitored subframe t_(z) ^(SL) in Step 2.        -   there is an integer j which meets            y+j×P′_(rsvp_TX)=z+P_(step)×k×q where j=0, 1, . . . ,            C_(resel)−1, P′_(rsvp_TX)=P_(step)×P_(rsvp_TX)/100, k is any            value allowed by the higher layer parameter            restrictResourceReservationPeriod and q=1,2, . . . , Q.            Here,

$Q = \frac{1}{k}$if k<1 and n′−z≤P_(step)×k, where t_(n′) ^(SL)=n if subframe n belongsto the set t₀ ^(SL), t₁ ^(SL), . . . , t_(T) _(max) ^(SL), otherwisesubframe t_(n′) ^(SL) is the first subframe belonging to the set t₀^(SL), t₁ ^(SL), . . . , t_(T) _(max) ^(SL) after subframe n; and Q=1otherwise.

-   -   6) The UE shall exclude any candidate single-subframe resource        R_(x,y) from the set S_(A) if it meets all the following        conditions:        -   the UE receives an SCI format 1 in subframe t_(m) ^(SL), and            “Resource reservation” field and “Priority” field in the            received SCI format 1 indicate the values P_(rsvp_RX) and            prio_(RX), respectively according to Subclause 14.2.1.        -   PSSCH-RSRP measurement according to the received SCI format            1 is higher than Th_(prio) _(TX) _(,prio) _(RX) .        -   the SCI format received in subframe t_(m) ^(SL) or the same            SCI format 1 which is assumed to be received in subframe(s)            t_(m+q×P) _(step) _(×P) _(rsvp_RX) determines according to            14.1.1.4C the set of resource blocks and subframes which            overlaps with R_(x, y+j×P) _(rsvp_TX) for q=1, 2, . . . , Q            and j=0, 1, . . . , C_(resel)−1. Here,

$Q = {{\frac{1}{P_{rsvp_{-}RX}}P_{rsvp_{-}RX}} < 1}$and n′−m≤P_(step)×P_(rsvp_RX), where t_(n′) ^(SL)=n if subframe nbelongs to the set (t₀ ^(SL), t₁ ^(SL), . . . , t_(T) _(max) ^(SL)),otherwise subframe t_(n′) ^(SL) is the first subframe after subframe nbelonging to the set (t₀ ^(SL), t₁ ^(SL), . . . , t_(T) _(max) ^(SL));otherwise Q=1.

-   -   7) If the number of candidate single-subframe resources        remaining in the set S_(A) is smaller than 0.2·M_(total), then        Step 4 is repeated with Th_(a,b) increased by 3 dB.    -   8) For a candidate single-subframe resource R_(x,y) remaining in        the set S_(A), the metric E_(x,y) is defined as the linear        average of S-RSSI measured in sub-channels x+k for k=0, . . . ,        L_(subCH)−1 in the monitored subframes in Step 2 that can be        expressed by

t_(y − P_(step) * j)^(SL)for a non-negative integer j if P_(rsvp)≥100, and

t_(y − P_(rsvp_TX)^(′) * j)^(SL)for a non negative integer j otherwise.

-   -   9) The UE moves the candidate single-subframe resource R_(x,y)        with the smallest metric E_(x,y) from the set S_(A) to S_(B).        This step is repeated until the number of candidate        single-subframe resources in the set S_(B) becomes greater than        or equal to 0.2·M_(total),    -   10) When the UE is configured by upper layers to transmit using        resource pools on multiple carriers, it shall exclude a        candidate single-subframe resource R_(x,y) from S_(B) if the UE        does not support transmission in the candidate single-subframe        resource in the carrier under the assumption that transmissions        take place in other carrier(s) using the already selected        resources due to its limitation in the number of simultaneous        transmission carriers, its limitation in the supported carrier        combinations, or interruption for RF retuning time [10].

The UE shall report set S_(B) to higher layers.

[ . . . ]

14.2 Physical Sidelink Control Channel Related Procedures

For sidelink transmission mode 1, if a UE is configured by higher layersto receive DCI format 5 with the CRC scrambled by the SL-RNTI, the UEshall decode the PDCCH/EPDCCH according to the combination defined inTable 14.2-1.

[Table 14.2-1 of 3GPP TS 36.213 V15.4.0, Entitled “PDCCH/EPDCCHConfigured by SL-RNTI”, is Reproduced as FIG. 5]

For sidelink transmission mode 3, if a UE is configured by higher layersto receive DCI format 5A with the CRC scrambled by the SL-V-RNTI orSL-SPS-V-RNTI, the UE shall decode the PDCCH/EPDCCH according to thecombination defined in Table 14.2-2. A UE is not expected to receive DCIformat 5A with size larger than DCI format 0 in the same search spacethat DCI format 0 is defined on.

[Table 14.2-2 of 3GPP TS 36.213 V15.4.0, Entitled “PDCCH/EPDCCHConfigured by SL-V-RNTI or SL-SPS-V-RNTI”, is Reproduced as FIG. 6]

The carrier indicator field value in DCI format 5A corresponds tov2x-InterFreqInfo.

14.2.1 UE Procedure for Transmitting the PSCCH

[ . . . ]

For sidelink transmission mode 3,

-   -   The UE shall determine the subframes and resource blocks for        transmitting SCI format 1 as follows:        -   SCI format 1 is transmitted in two physical resource blocks            per slot in each subframe where the corresponding PSSCH is            transmitted.        -   If the UE receives in subframe n DCI format 5A with the CRC            scrambled by the SL-V-RNTI, one transmission of PSCCH is in            the PSCCH resource L_(Init) (described in Subclause 14.2.4)            in the first subframe that is included in (t₀ ^(SL), t₁            ^(SL), t₂ ^(SL), . . . ) and that starts not earlier than

$T_{DL} - {\frac{N_{TA}}{2} \times T_{S}} + {\left( {4 + m} \right) \times {10^{- 3}.}}$L_(Init) is the value indicated by “Lowest index of the sub-channelallocation to the initial transmission” associated with the configuredsidelink grant (described in [8]), (t₀ ^(SL), t₁ ^(SL), t_(2hu SL), . .. ) is determined by Subclause 14.1.5, the value m is indicated by ‘SLindex’ field in the corresponding DCI format 5A according to Table14.2.1-1 if this field is present and m=0 otherwise, T_(DL) is the startof the downlink subframe carrying the DCI, and N_(TA) and T_(S) aredescribed in [3].

-   -   -   -   If “Time gap between initial transmission and                retransmission” in the configured sidelink grant                (described in [8]) is not equal to zero, another                transmission of PSCCH is in the PSCCH resource L_(ReTX)                in subframe t_(q+SF) _(gap) ^(SL), where SF_(gap) is the                value indicated by “Time gap between initial                transmission and retransmission” field in the configured                sidelink grant, subframe t_(q) ^(SL) corresponds to the                subframe n+k_(init). L_(ReTX) corresponds to the value                n_(subCH) ^(start) determined by the procedure in                Subclause 14.1.1.4C with the RIV set to the value                indicated by “Frequency resource location of the initial                transmission and retransmission” field in the configured                sidelink grant.

    -   The UE shall set the contents of the SCI format 1 as follows:        -   the UE shall set the Modulation and coding scheme as            indicated by higher layers.        -   the UE shall set the “Priority” field according to the            highest priority among those priority(s) indicated by higher            layers corresponding to the transport block.        -   the UE shall set the Time gap between initial transmission            and retransmission field, the Frequency resource location of            the initial transmission and retransmission field, and the            Retransmission index field such that the set of time and            frequency resources determined for PSSCH according to            Subclause 14.1.1.4C is in accordance with the PSSCH resource            allocation indicated by the configured sidelink grant.        -   the UE shall set the Resource reservation according to table            14.2.1-2 based on indicated value X, where X is equal to the            Resource reservation interval provided by higher layers            divided by 100.        -   Each transmission of SCI format 1 is transmitted in one            subframe and two physical resource blocks per slot of the            subframe.

    -   The UE shall randomly select the cyclic shift n_(cs,λ) among {0,        3, 6, 9} in each PSCCH transmission.

For sidelink transmission mode 4,

-   -   The UE shall determine the subframes and resource blocks for        transmitting SCI format 1 as follows:        -   SCI format 1 is transmitted in two physical resource blocks            per slot in each subframe where the corresponding PSSCH is            transmitted.        -   If the configured sidelink grant from higher layer indicates            the PSCCH resource in subframe t_(n) ^(SL), one transmission            of PSCCH is in the indicated PSCCH resource m (described in            Subclause 14.2.4) in subframe t_(n) ^(SL).        -   If “Time gap between initial transmission and            retransmission” in the configured sidelink grant (described            in [8]) is not equal to zero, another transmission of PSCCH            is in the PSCCH resource L_(ReTX) in subframe t_(n+SF)            _(gap) ^(SL) where SF_(gap) is the value indicated by “Time            gap between initial transmission and retransmission” field            in the configured sidelink grant, L_(ReTX) corresponds to            the value n_(subCh) ^(start) determined by the procedure in            Subclause 14.1.1.4C with the RIV set to the value indicated            by “Frequency resource location of the initial transmission            and retransmission” field in the configured sidelink grant.    -   the UE shall set the contents of the SCI format 1 as follows:        -   the UE shall set the Modulation and coding scheme as            indicated by higher layers.        -   the UE shall set the “Priority” field according to the            highest priority among those priority(s) indicated by higher            layers corresponding to the transport block.        -   the UE shall set the Time gap between initial transmission            and retransmission field, the Frequency resource location of            the initial transmission and retransmission field, and the            Retransmission index field such that the set of time and            frequency resources determined for PSSCH according to            Subclause 14.1.1.4C is in accordance with the PSSCH resource            allocation indicated by the configured sidelink grant.        -   the UE shall set the Resource reservation field according to            table 14.2.1-2 based on indicated value X, where X is equal            to the Resource reservation interval provided by higher            layers divided by 100.        -   Each transmission of SCI format 1 is transmitted in one            subframe and two physical resource blocks per slot of the            subframe.        -   The UE shall randomly select the cyclic shift n_(cs,λ) among            {0, 3, 6, 9} in each PSCCH transmission.            [Table 14.2.1-1 of 3GPP TS 36.213 V15.4.0, Entitled “Mapping            of DCI Format 5A Offset Field to Indicated Value m”, is            Reproduced as FIG. 7]            [Table 14.2.1-2 of 3GPP TS 36.213 V15.4.0, Entitled            “Determination of the Resource Reservation Field in SCI            Format 1”, is Reproduced as FIG. 8]            14.2.2 UE Procedure for Receiving the PSCCH

For each PSCCH resource configuration associated with sidelinktransmission mode 3, a UE configured by higher layers to detect SCIformat 1 on PSCCH shall attempt to decode the PSCCH according to thePSCCH resource configuration. The UE is not required to decode more thanone PSCCH at each PSCCH resource candidate. The UE shall not assume anyvalue for the “Reserved bits” before decoding a SCI format 1.

For each PSCCH resource configuration associated with sidelinktransmission mode 4, a UE configured by higher layers to detect SCIformat 1 on PSCCH shall attempt to decode the PSCCH according to thePSCCH resource configuration. The UE is not required to decode more thanone PSCCH at each PSCCH resource candidate. The UE shall not assume anyvalue for the “Reserved bits” before decoding a SCI format 1.

3GPP TS 36.212 specifies CRC attachment for downlink shared channel anddownlink control information in LTE/LTE-A (as shown below). The downlinkshared channel and downlink control information are for communicationbetween network node and UE, i.e. Uu link. The sidelink shared channeland sidelink control information are for communication between UEs, i.e.PC5 link or sidelink.

5.3.3.1.9A Format 5A

DCI format 5A is used for the scheduling of PSCCH, and also containsseveral SCI format 1 fields used for the scheduling of PSSCH.

The following information is transmitted by means of the DCI format 5A:

-   -   Carrier indicator −3 bits. This field is present according to        the definitions in [3].    -   Lowest index of the subchannel allocation to the initial        transmission −┌log₂(N_(subchannel) ^(SL))┐ bits as defined in        subclause 14.1.1.4C of [3].    -   SCI format 1 fields according to 5.4.3.1.2:        -   Frequency resource location of initial transmission and            retransmission.        -   Time gap between initial transmission and retransmission.    -   SL index −2 bits as defined in subclause 14.2.1 of [3] (this        field is present only for cases with TDD operation with        uplink-downlink configuration 0-6).

When the format 5A CRC is scrambled with SL-SPS-V-RNTI, the followingfields are present:

-   -   SL SPS configuration index −3 bits as defined in subclause        14.2.1 of [3].    -   Activation/release indication −1 bit as defined in subclause        14.2.1 of [3].

[ . . . ]

5.4.3 Sidelink Control Information

5.4.3.1 SCI Formats

The fields defined in the SCI formats below are mapped to theinformation bits a₀ to a_(A−1) as follows.

Each field is mapped in the order in which it appears in thedescription, with the first field mapped to the lowest order informationbit a₀ and each successive field mapped to higher order informationbits. The most significant bit of each field is mapped to the lowestorder information bit for that field, e.g. the most significant bit ofthe first field is mapped to a₀.

[ . . . ]

5.4.3.1.2 SCI format 1

SCI format 1 is used for the scheduling of PSSCH.

The following information is transmitted by means of the SCI format 1:

-   -   Priority −3 bits as defined in subclause 4.4.5.1 of [7].    -   Resource reservation −4 bits as defined in subclause 14.2.1 of        [3].    -   Frequency resource location of initial transmission and        retransmission −┌log₂(N_(subchannel) ^(SL) (N_(subchannel)        ^(SL)+1)/2)┐ bits as defined in subclause 14.1.1.4C of [3].    -   Time gap between initial transmission and retransmission −4 bits        as defined in subclause 14.1.1.4C of [3].    -   Modulation and coding scheme −5 bits as defined in subclause        14.2.1 of [3].    -   Retransmission index −1 bit as defined in subclause 14.2.1 of        [3].    -   Transmission format −1 bit, where value 1 indicates a        transmission format including rate-matching and TBS scaling, and        value 0 indicates a transmission format including puncturing and        no TBS-scaling. This field is only present if the transport        mechanism selected by higher layers indicates the support of        rate matching and TBS scaling.    -   Reserved information bits are added until the size of SCI format        1 is equal to 32 bits. The reserved bits are set to zero.

3GPP TS 36.211 specifies generation for physical sidelink shared channeland physical sidelink control channel in LTE/LTE-A (as shown below). Thephysical sidelink shared channel and physical sidelink control channelare for communication between devices, i.e. PC5 link or device-to-devicelink. The physical sidelink shared channel (PSSCH) deliversdata/transport block for sidelink shared channel (SL-SCH). The physicalsidelink control channel (PSCCH) delivers sidelink control information(SCI).

9 Sidelink

9.1 Overview

A sidelink is used for ProSe direct communication and ProSe directdiscovery between UEs.

9.1.1 Physical Channels

A sidelink physical channel corresponds to a set of resource elementscarrying information originating from higher layers and is the interfacedefined between 3GPP TS 36.212 [3] and the present document 3GPP TS36.211. The following sidelink physical channels are defined:

-   -   Physical Sidelink Shared Channel, PSSCH    -   Physical Sidelink Control Channel, PSCCH

Generation of the baseband signal representing the different physicalsidelink channels is illustrated in FIG. 5.3-1.

3GPP RP-191723 specifies the Justification and objective of study itemon NR V2X as follows:

3 Justification

To expand the 3GPP platform to the automotive industry, the initialstandard on support of V2V services was completed in September 2016.Enhancements that focusing on additional V2X operation scenariosleveraging the cellular infrastructure, are completed in March 2017 as3GPP V2X phase 1 for inclusion in Release 14 LTE. In Rel-14 LTE V2X, abasic set of requirements for V2X service in TS 22.185 derived from TR22.885 has been supported, which are considered sufficient for basicroad safety service. Vehicles (i.e., UEs supporting V2X applications)can exchange their own status information through sidelink, such asposition, speed and heading, with other nearby vehicles, infrastructurenodes and/or pedestrians.

3GPP V2X phase 2 in Rel-15 introduces a number of new features insidelink, including: carrier aggregation, high order modulation, latencyreduction, and feasibility study on both transmission diversity andshort TTI in sidelink. All these enhanced features in 3GPP V2X phase 2are primary base on LTE and require co-existing with Rel-14 UE in sameresource pool.

SA1 has completed enhancement of 3GPP support for V2X services (eV2Xservices) in Rel-15. The consolidated requirements for each use casegroup (see below) are captured in TR 22.886, and a set of the normativerequirements are defined in TS 22.186 in Rel-15.

SA1 has identified 25 use cases for advanced V2X services and they arecategorized into four use case groups: vehicles platooning, extendedsensors, advanced driving and remote driving. The detailed descriptionof each use case group is provided as below.

-   -   Vehicles Platooning enables the vehicles to dynamically form a        group travelling together. All the vehicles in the platoon        receive periodic data from the leading vehicle, in order to        carry on platoon operations. This information allows the        distance between vehicles to become extremely small, i.e., the        gap distance translated to time can be very low (sub second).        Platooning applications may allow the vehicles following to be        autonomously driven.    -   Extended Sensors enables the exchange of raw or processed data        gathered through local sensors or live video data among        vehicles, RSUs, devices of pedestrians and V2X application        servers. The vehicles can enhance the perception of their        environment beyond what their own sensors can detect and have a        more holistic view of the local situation.    -   Advanced Driving enables semi-automated or fully-automated        driving. Longer inter-vehicle distance is assumed. Each vehicle        and/or RSU shares data obtained from its local sensors with        vehicles in proximity, thus allowing vehicles to coordinate        their trajectories or maneuvers. In addition, each vehicle        shares its driving intention with vehicles in proximity. The        benefits of this use case group are safer traveling, collision        avoidance, and improved traffic efficiency.    -   Remote Driving enables a remote driver or a V2X application to        operate a remote vehicle for those passengers who cannot drive        themselves or a remote vehicle located in dangerous        environments. For a case where variation is limited and routes        are predictable, such as public transportation, driving based on        cloud computing can be used. In addition, access to cloud-based        back-end service platform can be considered for this use case        group.        4 Objective        4.1 Objective of SI or Core Part WI or Testing Part WI

The objective of this work item is to specify radio solutions that arenecessary for NR to support advanced V2X services (except the remotedriving use case which was studied in TR 38.824) based on the studyoutcome captured in TR 38.885.

1. NR sidelink: Specify NR sidelink solutions necessary to supportsidelink unicast, sidelink groupcast, and sidelink broadcast for V2Xservices, considering in-network coverage, out-of-network coverage, andpartial network coverage.

-   -   Support of sidelink signals, channels, bandwidth part, and        resource pools [RAN1, RAN2]    -   Resource allocation [RAN1, RAN2]        -   Mode 1            -   NR sidelink scheduling by NR Uu and LTE Uu as per the                study outcome        -   Mode 2            -   Sensing and resource selection procedures based on                sidelink pre-configuration and configuration by NR Uu                and LTE Uu as per the study outcome        -   Support for simultaneous configuration of Mode 1 and Mode 2            for a UE            -   Transmitter UE operation in this configuration is to be                discussed after the design of mode 1 only and mode 2                only.            -   Receiver UE can receive the transmissions without                knowing the resource allocation mode used by the                transmitter UE.        -   UE relaying resource pool configuration or resource            configuration is not supported in this work in Rel-16.    -   Sidelink synchronization mechanism as per the study outcome        [RAN1, RAN2]        -   Procedures selecting synchronization reference        -   S-SSB and procedures to transmit and receive it, including            when GNSS and gNB/eNB are unavailable        -   Use of RS for sidelink synchronization if specification            impact is identified    -   Solutions for ‘not co-channel’ in-device coexistence between LTE        and NR sidelinks        -   TDM-based solutions as per the study outcome [RAN1, RAN2,            RAN4]        -   FDM-based solutions with static power allocation as per the            study outcome [RAN4]            -   This will not consider the case where LTE and NR                sidelinks are in the same frequency band.        -   No impact to LTE specifications at least from RAN1 and RAN2            perspective.    -   Sidelink physical layer procedures as per the study outcome        -   HARQ procedures [RAN1, RAN2]        -   CSI acquisition for unicast [RAN1]            -   CQI/RI reporting is supported and they are always                reported together. No PMI reporting is supported in this                work. Multi-rank PSSCH transmission is supported up to                two antenna ports.            -   In sidelink, CSI is delivered using PSSCH (including                PSSCH containing CSI only) using the resource allocation                procedure for data transmission.        -   Power control [RAN1, RAN2]    -   Congestion control [RAN1, RAN2]    -   Sidelink L2/L3 protocols and signalling        -   Support of sidelink transmission and reception in RRC, MAC,            RLC, PDCP, and SDAP [RAN2]        -   AS level link management for unicast [RAN2, RAN1]            -   Define the criteria of PC5 availability/unavailability                for unicast based on this functionality.    -   Network solutions to support NR sidelink        -   V2X service authorization [RAN3]        -   F1 signalling for support of NR V2X [RAN3]        -   Resource coordination between NG-RAN nodes for V2X sidelink            communication, taking into consideration previous RAN3            discussions [RAN3]    -   UE Tx and Rx RF requirement [RAN4]        -   This requirement should ensure            -   coexistence between sidelink and Uu interface in the                same and adjacent channels in licensed spectrum        -   coexistence with other V2X technologies in the adjacent            channel in ITS spectrum in 5.9 GHz, without assuming that            5.9 GHz spectrum will be universally available nor that it            will be universally available in sufficient quantity to            support NR V2X advanced use cases    -   RRM core requirement [RAN4]

The solutions should cover both the operating scenario where thecarrier(s) is/are dedicated to V2X services and the operating scenariowhere the carrier(s) is/are licensed spectrum and also used for NRUu/LTE Uu operation.

NR sidelink design starts with frequencies in FR1, and NR sidelink inFR2 is supported by applying the design for FR1 and PT-RS to thenumerologies agreed for FR2. No FR2 specific optimization is supportedin this WI except PT-RS. No beam management is supported in this work.

For the scenarios of NR sidelink carrier, this work will consider asingle carrier for the NR sidelink transmission and reception.

In this work, 2Rx antennas as well as 4Rx antennas are supported. Thefull range of speeds defined in SA1 (TS 22.186) needs to be supported inFR1.

It is assumed that any co-channel coexistence requirements andmechanisms of NR sidelink with non-3GPP technologies will not be definedby 3GPP.

In the RAN1 #94 meeting (as captured in 3GPP R1-1810051), RAN1 has thefollowing agreements about NR V2X:

Agreements:

-   -   RAN1 assumes that higher layer decides if a certain data has to        be transmitted in a unicast, groupcast, or broadcast manner and        inform the physical layer of the decision. For a transmission        for unicast or groupcast, RAN1 assumes that the UE has        established the session to which the transmission belongs to.        Note that RAN1 has not made agreement about the difference among        transmissions in unicast, groupcast, and broadcast manner.    -   RAN1 assumes that the physical layer knows the following        information for a certain transmission belonging to a unicast or        groupcast session. Note RAN1 has not made agreement about the        usage of this information.        -   ID            -   Groupcast: destination group ID, FFS: source ID            -   Unicast: destination ID, FFS: source ID            -   HARQ process ID (FFS for groupcast)        -   RAN1 can continue discussion on other information

Agreements:

-   -   RAN1 to study the following topics for the SL enhancement for        unicast and/or groupcast. Other topics are not precluded.        -   HARQ feedback        -   CSI acquisition        -   Open loop and/or closed-loop power control        -   Link adaptation        -   Multi-antenna transmission scheme

[ . . . ]

R1-1809799 Offline summary for 7.2.4.1.2 Physical layer structures andprocedure(s) LGE

Agreements:

-   -   At least PSCCH and PSSCH are defined for NR V2X. PSCCH at least        carries information necessary to decode PSSCH.        -   Note: PSBCH will be discussed in the synchronization agenda.

[ . . . ]

Agreements:

RAN1 to continue study on multiplexing physical channels considering atleast the above aspects:

-   -   Multiplexing of PSCCH and the associated PSSCH (here, the        “associated” means that the PSCCH at least carries information        necessary to decode the PSSCH).        -   Study further the following options:            -   [ . . . ]            -   Option 3: A part of PSCCH and the associated PSSCH are                transmitted using overlapping time resources in                non-overlapping frequency resources, but another part of                the associated PSSCH and/or another part of the PSCCH                are transmitted using non-overlapping time resources.

[ . . . ]

Agreements:

-   -   At least two sidelink resource allocation modes are defined for        NR-V2X sidelink communication        -   Mode 1: Base station schedules sidelink resource(s) to be            used by UE for sidelink transmission(s)        -   Mode 2: UE determines (i.e. base station does not schedule)            sidelink transmission resource(s) within sidelink resources            configured by base station/network or pre-configured            sidelink resources

In the RAN1 #94bis meeting (as captured in 3GPP R1-1812101), RAN1 hasthe following agreements about NR V2X:

Agreements:

-   -   Layer-1 destination ID is conveyed via PSCCH.    -   Additional Layer-1 ID(s) is conveyed via PSCCH at least for the        purpose of identifying which transmissions can be combined in        reception when HARQ feedback is in use.

Agreements:

-   -   For unicast, sidelink HARQ feedback and HARQ combining in the        physical layer are supported.    -   For groupcast, sidelink HARQ feedback and HARQ combining in the        physical layer are supported.

Agreements:

-   -   Sidelink control information (SCI) is defined.        -   SCI is transmitted in PSCCH.        -   SCI includes at least one SCI format which includes the            information necessary to decode the corresponding PSSCH.            -   NDI, if defined, is a part of SCI.    -   Sidelink feedback control information (SFCI) is defined.    -   SFCI includes at least one SFCI format which includes HARQ-ACK        for the corresponding PSSCH.

Agreements:

-   -   At least resource pool is supported for NR sidelink        -   Resource pool is a set of time and frequency resources that            can be used for sidelink transmission and/or reception.            -   A resource pool is inside the RF bandwidth of the UE.        -   UE assumes a single numerology in using a resource pool.        -   Multiple resource pools can be configured to a single UE in            a given carrier.

In the RAN1 #95 meeting (as captured in 3GPP R1-1901482), RAN1 has thefollowing agreements about NR V2X:

Agreements:

-   -   At least CP-OFDM is supported.    -   Continue study on whether to support DFT-S-OFDM including the        potential issues and the following potential benefit:        -   Synchronization coverage enhancement        -   PSCCH coverage enhancement, e.g., with Option 2 of            PSCCH/PSSCH multiplexing with the restriction that PSCCH and            PSSCH use adjacent frequency resources        -   Feedback channel coverage enhancement    -   A single waveform is used in all the sidelink channels in a        carrier.        -   Note: A sequence based channel can be supported in any            waveform.        -   (Pre-)configuration will be used to determine the used            waveform if the specification supports multiple waveforms.

Agreements:

-   -   BWP is defined for NR sidelink.        -   In a licensed carrier, SL BWP is defined separately from BWP            for Uu from the specification perspective.            -   FFS the relation with Uu BWP.        -   The same SL BWP is used for both Tx and Rx.        -   Each resource pool is (pre)configured within a SL BWP.        -   Only one SL BWP is (pre)configured for RRC idle or out of            coverage NR V2X UEs in a carrier.        -   For RRC connected UEs, only one SL BWP is active in a            carrier. No signalling is exchanged in sidelink for            activation and deactivation of SL BWP.            -   Working assumption: only one SL BWP is configured in a                carrier for a NR V2X UE                -   Revisit in the next meeting if significant issues                    are found        -   Numerology is a part of SL BWP configuration.

Note: This does not intend to make restriction in designing the sidelinkaspects related to SL BWP.

Note: This does not preclude the possibility where a NR V2X UE uses a TxRF bandwidth the same as or different than the SL BWP.

Working assumption:

-   -   Regarding PSCCH/PSCCH multiplexing, at least option 3 is        supported for CP-OFDM.        -   RAN1 assumes that transient period is not needed between            symbols containing PSCCH and symbols not containing PSCCH in            the supported design of option 3.        -   [ . . . ]

Agreements:

-   -   Physical sidelink feedback channel (PSFCH) is defined and it is        supported to convey SFCI for unicast and groupcast via PSFCH.

Agreements:

-   -   When SL HARQ feedback is enabled for unicast, the following        operation is supported for the non-CBG case:        -   Receiver UE generates HARQ-ACK if it successfully decodes            the corresponding TB. It generates HARQ-NACK if it does not            successfully decode the corresponding TB after decoding the            associated PSCCH which targets the receiver UE.            [ . . . ]

Agreements:

-   -   When SL HARQ feedback is enabled for groupcast, the following        operations are further studied for the non-CBG case:        -   Option 1: Receiver UE transmits HARQ-NACK on PSFCH if it            fails to decode the corresponding TB after decoding the            associated PSCCH. It transmits no signal on PSFCH otherwise.            Details are FFS including the following:        -   Option 2: Receiver UE transmits HARQ-ACK on PSFCH if it            successfully decodes the corresponding TB. It transmits            HARQ-NACK on PSFCH if it does not successfully decode the            corresponding TB after decoding the associated PSCCH which            targets the receiver UE. Details are FFS including the            following:

Agreements:

-   -   It is supported to enable and disable SL HARQ feedback in        unicast and groupcast.

Agreements:

-   -   Study further whether to support UE sending to gNB information        which may trigger scheduling retransmission resource in mode 1.        FFS including        -   Which information to send        -   Which UE to send to gNB        -   Which channel to use        -   Which resource to use

Agreements:

The following NR sidelink resource allocation techniques by NR Uu formode-1 are supported:

-   -   Dynamic resource allocation    -   Configured grant.        -   FFS whether type-1 and/or type-2

In the RAN1 #AH_1901 meeting (as captured in 3GPP R1-1901483), RAN1 hasthe following agreements about NR V2X:

Agreements:

-   -   For time domain resources of a resource pool for PSSCH,        -   Support the case where the resource pool consists of            non-contiguous time resources    -   For frequency domain resources of a resource pool for PSSCH,        -   Down select following options:            -   Option 1: The resource pool always consists of                contiguous PRBs            -   Option 2: The resource pool can consist of                non-contiguous PRBs

Agreements:

-   -   Layer-1 destination ID can be explicitly included in SCI    -   The following additional information can be included in SCI        -   Layer-1 source ID            -   FFS how to determine Layer-1 source ID            -   FFS size of Layer-1 source ID        -   HARQ process ID        -   NDI        -   RV

Agreements:

-   -   For determining the resource of PSFCH containing HARQ feedback,        support that the time gap between PSSCH and the associated PSFCH        is not signaled via PSCCH at least for modes 2(a)(c)(d) (if        respectively supported)

[ . . . ]

Working assumption:

-   -   When HARQ feedback is enabled for groupcast, support (options as        identified in RAN1#95):        -   Option 1: Receiver UE transmits only HARQ NACK        -   Option 2: Receiver UE transmits HARQ ACK/NACK

Agreements:

-   -   It is supported that in mode 1 for unicast, the in-coverage UE        sends an indication to gNB to indicate the need for        retransmission        -   At least PUCCH is used to report the information            -   If feasible, RAN1 reuses PUCCH defined in Rel-15        -   The gNB can also schedule re-transmission resource

[ . . . ]

Agreements:

-   -   (Pre-)configuration indicates whether SL HARQ feedback is        enabled or disabled in unicast and/or groupcast.        -   When (pre-)configuration enables SL HARQ feedback, FFS            whether SL HARQ feedback is always used or there is            additional condition of actually using SL HARQ feedback

Agreements:

-   -   Sub-channel based resource allocation is supported for PSSCH        -   FFS details for sub-channels        -   FFS other use cases for sub-channel (e.g., measurement,            interaction with PSCCH, etc.)

Agreements:

-   -   SCI decoding applied during sensing procedure provides at least        information on sidelink resources indicated by the UE        transmitting the SCI

Agreements:

-   -   When NR Uu schedules NR SL mode 1, both type 1 and type 2        configured grants are supported for NR SL

In the RAN1 #96 meeting (as captured in 3GPP R1-1905837), RAN1 has thefollowing agreements about NR V2X:

Agreements:

-   -   Rel-16 NR sidelink supports CP-OFDM only.

Agreements:

-   -   For the operation regarding PSSCH, a UE performs either        transmission or reception in a slot on a carrier.    -   NR sidelink supports for a UE:        -   A case where all the symbols in a slot are available for            sidelink.        -   Another case where only a subset of consecutive symbols in a            slot is available for sidelink            -   Note: this case is not intended to be used for the ITS                spectra, if there is no forward-compatibility issue.                Finalize in the WI phase whether there is such an issue                or not            -   The subset is NOT dynamically indicated to the UE

Agreements:

-   -   At least for sidelink HARQ feedback, NR sidelink supports at        least a PSFCH format which uses last symbol(s) available for        sidelink in a slot.

Agreements:

-   -   (Pre-)configuration indicates the time gap between PSFCH and the        associated PSSCH for Mode 1 and Mode 2.

Agreements:

-   -   For sidelink groupcast, it is supported to use TX-RX distance        and/or RSRP in deciding whether to send HARQ feedback.        -   Details to be discussed during WI phase, including whether            the information on TX-RX distance is explicitly signaled or            implicitly derived, whether/how this operation is related to            resource allocation, accuracy of distance and/or RSRP, the            aspects related to “and/or”, etc.        -   This feature can be disabled/enabled

Agreements:

-   -   Blind retransmissions of a TB are supported for SL by NR-V2X

Agreements:

-   -   NR V2X Mode-2 supports reservation of sidelink resources at        least for blind retransmission of a TB

Agreements:

-   -   Mode-2 sensing procedure utilizes the following sidelink        measurement        -   L1 SL-RSRP based on sidelink DMRS when the corresponding SCI            is decoded            -   FFS whether/which measurement is used if the                corresponding SCI is not decoded e.g. SL-RSRP after                blind DMRS detection, SL-RSSI

In the RAN1 #96bis meeting (as captured in 3GPP R1-1905921), RAN1 hasthe following agreements about NR V2X:

Agreements:

-   -   At least for transmission perspective of a UE in a carrier, at        least TDM between PSCCH/PSSCH and PSFCH is allowed for a PSFCH        format for sidelink in a slot.

[ . . . ]

Agreements:

-   -   A dynamic grant provides resources for one or multiple sidelink        transmissions of a single TB.    -   A configured grant (type-1, type-2) provides a set of resources        in a periodic manner for multiple sidelink transmissions.        -   UE decides which TB to transmit in each of the occasions            indicated by a given configured grant.        -   [ . . . ]

Agreements:

-   -   NR V2X supports an initial transmission of a TB without        reservation, based on sensing and resource selection procedure    -   NR V2X supports reservation of a sidelink resource for an        initial transmission of a TB at least by an SCI associated with        a different TB, based on sensing and resource selection        procedure        -   This functionality can be enabled/disabled by            (pre-)configuration    -   FFS Standalone PSCCH transmissions for resource reservations are        supported in NR V2X

[ . . . ]

Agreements:

-   -   Confirm the following working assumption:        -   Working assumption:            -   When HARQ feedback is enabled for groupcast, support                (options as identified in RAN1#95):                -   Option 1: Receiver UE transmits only HARQ NACK            -   Option 2: Receiver UE transmits HARQ ACK/NACK    -   Note: RAN1 has not concluded the respective applicability of        option 1 vs. option 2 yet

Agreements:

-   -   In HARQ feedback for groupcast,        -   When Option 1 is used for a groupcast transmission, it is            supported            -   all the receiver UEs share a PSFCH            -   FFS: a subset of the receiver UEs share a PSFCH            -   FFS: all or a subset of receiver UEs share a pool of                PSFCH.        -   When Option 2 is used for a groupcast transmission, it is            supported            -   each receiver UE uses a separate PSFCH for HARQ                ACK/NACK.            -   FFS: all or a subset of receiver UEs share a PSFCH for                ACK transmission and another PSFCH for NACK transmission    -   Note: Each PSFCH is mapped to a time, frequency, and code        resource.

Working assumption:

-   -   Regarding the use of TX-RX geographical distance and/or RSRP in        determining whether to send HARQ feedback for groupcast        -   Support at least the use of TX-RX geographical distance

Agreements:

-   -   It is supported, in a resource pool, that within the slots        associated with the resource pool, PSFCH resources can be        (pre)configured periodically with a period of N slot(s)        -   N is configurable, with the following values            -   1            -   At least one more value >1                -   FFS details        -   The configuration should also include the possibility of no            resource for PSFCH. In this case, HARQ feedback for all            transmissions in the resource pool is disabled    -   HARQ feedback for transmissions in a resource pool can only be        sent on PSFCH in the same resource pool

In the RAN1 #97 meeting (as captured in 3GPP R1-1907973), RAN1 has thefollowing agreements about NR V2X:

Agreements:

-   -   Transmission of PSSCH is mapped onto contiguous PRBs only

Agreements:

-   -   Sub-channel size is (pre)configurable.

Conclusion:

-   -   If two-stage SCI is supported, the following details are used.        -   Information related to channel sensing is carried on            1st-stage.        -   2nd-stage is decoded by using PSSCH DMRS.        -   Polar coding used for PDCCH is applied to 2nd-stage        -   Payload size for 1st-stage in two-stage SCI case is the same            for unicast, groupcast, and broadcast in a resource pool.        -   After decoding the 1st-stage, the receiver does not need to            perform blind decoding of 2nd-stage.            [ . . . ]

Agreements:

-   -   Sidelink HARQ ACK/NACK report from transmitter UE to gNB is        supported with details FFS.        -   Note: this reverts the following agreement from RAN1#96:            -   Sidelink HARQ ACK/NACK report from UE to gNB is not                supported in Rel-16.    -   SR/BSR report to gNB for the purpose of requesting resources for        HARQ retransmission is not supported.

Agreements:

-   -   NR sidelink does not support performing different transmissions        of a TB using different configured grants.

Agreements:

-   -   For mode 1:        -   A dynamic grant by the gNB provides resources for            transmission of PSCCH and PSSCH.

[ . . . ]

Agreements:

-   -   RAN1 to further select between the following options of sidelink        resource reservation for blind retransmissions:        -   Option 1: A transmission can reserve resources for none,            one, or more than one blind retransmission        -   Option 2: A transmission can reserve resource for none or            one blind retransmission

Agreements:

-   -   For at least option 1 based TX-RX distance-based HARQ feedback        for groupcast,        -   A UE transmits HARQ feedback for the PSSCH if TX-RX distance            is smaller or equal to the communication range requirement.            Otherwise, the UE does not transmit HARQ feedback for the            PSSCH            -   TX UE's location is indicated by SCI associated with the                PSSCH.            -   The TX-RX distance is estimated by RX UE based on its                own location and TX UE location.            -   The used communication range requirement for a PSSCH is                known after decoding SCI associated with the PSSCH

Agreements:

-   -   For the period of N slot(s) of PSFCH resource, N=2 and N=4 are        additionally supported.

Agreements:

-   -   For a PSSCH transmission with its last symbol in slot n, when        the corresponding HARQ feedback is due for transmission, it is        expected to be in slot n+a where a is the smallest integer        larger than or equal to K with the condition that slot n+a        contains PSFCH resources.        -   FFS details of K

Agreements:

-   -   At least for the case when the PSFCH in a slot is in response to        a single PSSCH:        -   Implicit mechanism is used to determine at least frequency            and/or code domain resource of PSFCH, within a configured            resource pool. At least the following parameters are used in            the implicit mechanism:            -   Slot index (FFS details) associated with                PSCCH/PSSCH/PSFCH            -   Sub-channel(s) (FFS details) associated with PSCCH/PSSCH            -   Identifier (FFS details) to distinguish each RX UE in a                group for Option 2 groupcast HARQ feedback

In the RAN1 #98 meeting (as captured in 3GPP R1-1909942), RAN1 has thefollowing agreements about NR V2X:

Agreements:

-   -   In physical layer perspective, a (pre-)configured resource pool        can be used for all of unicast, groupcast, and broadcast for a        given UE.        -   There is no (pre-)configuration to inform which cast types            are used for the resource pool.

Agreements:

-   -   Support 2-stage SCI        -   1^(st) SCI is carried in PSCCH.        -   FFS: other details

Agreements:

-   -   For Mode-1, support both same-carrier & cross-carrier scheduling        from gNB to NR SL        -   Whether or not to have the cross-carrier scheduling            indicator in the DCI given that there is only one SL carrier            for a UE in Rel-16

Agreements:

-   -   At least for dynamic grant, the timing and resource for PUCCH        used for conveying SL HARQ feedback to the gNB are based on the        indication(s) in the corresponding PDCCH

Agreements:

-   -   DCI indicates the slot offset between DCI reception and the        first sidelink transmission scheduled by DCI.        -   The minimum gap between DCI and the first scheduled sidelink            transmission is not smaller than the corresponding UE            processing time.        -   [ . . . ]

Agreements:

-   -   At least for mode 2, The maximum number of SL resources N_(MAX)        reserved by one transmission including current transmission is        [2 or 3 or 4]        -   Aim to select the particular number in RAN1#98    -   N_(MAX) is the same regardless of whether HARQ feedback is        enabled or disabled

Agreements:

-   -   At least for mode 2, (Pre-)configuration can limit the maximum        number of HARQ (re-)transmissions of a TB        -   Up to 32        -   FFS the set of values        -   FFS signaling details (UE-specific, resource pool specific,            QoS specific, etc.)        -   If no (pre)configuration, the maximum number is not            specified        -   Note: this (pre-)configuration information is NOT intended            for the Rx UE

Agreements:

-   -   In Mode-2, SCI payload indicates sub-channel(s) and slot(s) used        by a UE and/or reserved by a UE for PSSCH (re-)transmission(s)    -   SL minimum resource allocation unit is a slot    -   FFS whether when the resource allocation is multiple slots, the        slots can be aggregated    -   FFS whether in case of multiple slots, the indicated slots are        contiguous or not

Working assumption:

-   -   An indication of a priority of a sidelink transmission is        carried by SCI payload        -   This indication is used for sensing and resource            (re)selection procedures        -   This priority is not necessarily the higher layer priority

Agreements:

-   -   The resource (re-)selection procedure includes the following        steps        -   Step 1: Identification of candidate resources within the            resource selection window            -   FFS details        -   Step 2: Resource selection for (re-)transmission(s) from the            identified candidate resources            -   FFS details

[ . . . ]

Agreements:

-   -   For PSSCH-to-HARQ feedback timing, to down-select:        -   Option 1: K is the number of logical slots (i.e., the slots            within the resource pool)        -   Option 2: K is the number of physical slots (i.e., the slots            within and outside the resource pool)        -   FFS how to determine K.

Agreements:

-   -   For TX-RX distance-based HARQ feedback for groupcast Option 1,        -   The location information of TX UE is indicated by the 2^(nd)            stage SCI payload            -   FFS whether/how higher layer signaling is also used in                signaling the location information        -   FFS whether/how to handle when the location information is            not available at TX and/or RX UE.

As for the email discussion after the RAN1 #98 meeting, RAN1 has thefollowing agreements about NR V2X:

Agreements in [98-NR-10]:

-   -   In Rel-16, at least for sequence-based PSFCH format with one        symbol (not including AGC training period), it is not supported        to do FDM between PSSCH/PSCCH and PSFCH.    -   Discuss further the following:        -   For a PSFCH format, in the symbols that can be used for            PSFCH transmissions in a resource pool, a set of frequency            resources is (pre-)configured for the actual use of PSFCH            transmissions (i.e., PSFCH transmissions do not happen in            other frequency resources).            -   FFS: Frequency resource sets for PSFCH are separated                depending on HARQ feedback option.    -   At least, it is supported to use a single K value for all UEs in        a RX resource pool        -   K=2 is supported        -   FFS: whether to support other K values to be used as a            single K value in a resource pool        -   FFS: whether to support the use of multiple K values in a            resource pool    -   For implicit mechanism for PSFCH resource determination,        -   Support FDM between PSFCH resources used for HARQ feedback            of PSSCH transmissions with different starting sub-channel            in the same slot        -   Support FDM between PSFCH resources used for HARQ feedback            of PSSCH transmissions with different starting            sub-channel(s) in different slots        -   FFS: Support FDM between PSFCH resources used for HARQ            feedback of PSSCH transmissions with same starting            sub-channel in different slots        -   FFS whether/when to support CDM between PSFCH resources used            for HARQ feedback of PSSCH transmissions (e.g., when PSFCH            resource is insufficient)        -   For groupcast HARQ feedback Option 2, support CDM and FDM            between PSFCH resources used by different RX UEs for HARQ            feedback of the same PSSCH transmission        -   FFS how to multiplex HARQ feedback for unicast, groupcast            option 1, and groupcast option 2.

In the RAN1 #98bis meeting (as captured in 3GPP R1-1913275), RAN1 hasthe following agreements about NR V2X:

Agreements:

-   -   A slot is the time-domain granularity for resource pool        configuration.        -   To down-select:            -   Alt 1. Slots for a resource pool is (pre-)configured                with bitmap, which is applied with periodicity            -   Alt 2. Slots for a resource pool is (pre-)configured,                where the slots are applied with periodicity.

Agreements:

-   -   Support (pre-)configuration of a resource pool consisting of        contiguous PRBs only

Agreements:

-   -   For the number of bits of L1 IDs,        -   Layer-1 destination ID: 16 bits        -   Layer-1 source ID: 8 bits

Agreements:

[ . . . ]

-   -   Each resource pool is only configured with one 1^(st) stage SCI        PSCCH format

Agreements:

-   -   PSCCH for 1^(st) stage SCI with 2 and 3 symbols is supported in        Rel-16.        -   FFS: other length(s) of symbols (e.g., all symbols)        -   The number of symbols above excludes AGC symbols if any    -   The number of PSCCH symbols is explicitly (pre-)configured per        Tx/Rx resource pool

[ . . . ]

Agreements:

-   -   The 2^(nd) stage SCI is carried within the resource of the        corresponding PSSCH.    -   Scrambling operation for the 2^(nd) stage SCI is applied        separately with PSSCH

Agreements:

-   -   Support 1^(st) stage SCI in PSCCH in one subchannel only.        -   Within one subchannel, there is at most one 1^(st) stage            SCI, except for spatial re-use

Agreements:

-   -   Support {10, 15, 20, 25, 50, 75, 100} PRBs for possible        sub-channel size.        -   FFS other values (e.g., 4, 5, 6, etc.)    -   One value of the above set is (pre)configured for the        sub-channel size for the resource pool.    -   Size of PSCCH: X        -   X≤N, where N is the number of PRBs of the subchannel        -   X is (pre)-configurable with values FFS, X

Agreements:

-   -   To signal the gap between DCI reception and the first sidelink        transmission scheduled by DCI:        -   A table of values is configured by RRC.        -   DCI determines which of the configured values is used.        -   FFS how to determine the slot for the first sidelink            transmission (e.g., based on the indicated value, potential            async between Uu & SL, different numerologies, etc.)        -   FFS if the gap is in physical or logical slots.

Agreements:

For reporting SL HARQ-ACK to the gNB:

-   -   For dynamic grant and configured grant type-2 in SL, the Rel-15        procedure and signalling for DL HARQ-ACK are reused for the        purpose of selecting PUCCH offset/resource and format in UL.        -   The configuration for SL is separate from Uu link for a UE        -   FFS how to indicate timing of transmission in PUCCH,            including whether physical or logical slots are used    -   For configured grant type-1 in SL, RRC is used to configure        PUCCH offset/resource and format in UL (if supported)

Agreements:

-   -   Two different UE-specific SL RNTIs are introduced for Mode-1        scheduling: one for CRC scrambling in DCI for a dynamic grant        and the other one for CRC scrambling in DCI for a configured        grant type-2.        -   The two above DCIs have the same size

Agreements:

-   -   Multiple type-1 configured grants per UE are supported when LTE        Uu controls NR SL        -   Up to the same max number of type-1 configured grants per UE            when NR Uu controls NR SL

Working assumption:

-   -   Each transmission in a resource provided by a configured grant        contains PSCCH and PSSCH.

Agreements:

-   -   For a configured grant in Mode 1 when using SL HARQ feedback:        -   There is only one HARQ-ACK bit for the configured grant        -   There is one PUCCH transmission occasion after the last            resource in the set of resources provided by a configured            grant.

Agreements:

-   -   Maximum number of HARQ (re-)transmissions is (pre-)configured        per priority per CBR range per transmission resource pool        -   The priority is the one signaled in SCI        -   This includes both blind and feedback-based HARQ            (re)-transmission    -   The value range is any value from 1 to 32        -   If the HARQ (re)transmissions for a TB can have a mixed            blind and feedback-based approached (FFS whether or not to            support this case), the counter applies to the combined            total

Agreements:

-   -   For PSSCH-to-HARQ feedback timing, K is the number of logical        slots (i.e. the slots within the resource pool)

Working assumption:

-   -   For TX-RX distance-based HARQ feedback for groupcast Option 1,        -   Zone is (pre-)configured with respect to geographical area,            and Zone ID associated with TE UE's location is indicated by            SCI.            -   Details FFS            -   Note: this does not intend to impact the discussion on                the zone based resource allocation.

Agreements:

-   -   For the communication range requirement for TX-RX distance-based        HARQ feedback, explicit indication in the 2^(nd) stage SCI is        used.

Working assumption:

-   -   For HARQ feedback in groupcast and unicast, when PSFCH resource        is (pre-)configured in the resource pool,        -   SCI explicitly indicates whether HARQ feedback is used or            not for the corresponding PSSCH transmission.

Agreements:

-   -   For the priority indication in 1^(st) stage SCI:        -   Up to RAN2 on how to define the mapping between the priority            indication and the corresponding QoS        -   Size is 3 bits (as a working assumption)

In the RAN1 #99 meeting (as captured in the Draft Report of 3GPP TSG RANWG1 #99), RAN1 has the following agreements about NR V2X:

Agreements:

-   -   1st SCI includes at least        -   Priority (QoS value),        -   PSSCH resource assignment (frequency/time resource for            PSSCH),        -   Resource reservation period (if enabled),        -   PSSCH DMRS pattern (if more than one patterns are            (pre-)configured),        -   2nd SCI format (e.g. information on the size of 2nd SCI),        -   [2]-bit information on amount of resources for 2^(nd) SCI            (e.g. beta offset or aggregation level)        -   Number of PSSCH DMRS port(s)        -   5-bit MCS        -   FFS on some part of destination ID

Agreements:

-   -   For Rel-16, (normal CP)        -   Support 7, 8, 9, . . . , 14 symbols in a slot without SL-SSB            for SL operation            -   Target reusing Uu DM-RS patterns for each of the                symbol-length, with modifications as necessary                -   No other additional spec impact is expected for                    supporting 7, 8, . . . , 13                -   # of DM-RS symbols                -    2, 3, 4        -   For a dedicated carrier, only 14-symbol is mandatory    -   There is a single (pre-)configured length of SL symbols in a        slot without SL-SSB per SL BWP.    -   There is a single (pre-)configured starting symbol for SL in a        slot without SL-SSB per SL BWP.

Agreements:

-   -   From RAN1 perspective, a configured grant for SL can carry a TB        for which SL HARQ FB is enabled or disabled.        -   For any CG, if there is a possibility to carry a TB with SL            HARQ FB being enabled, there is always a corresponding PSFCH            configuration            -   A TB with SL HARQ FB is enabled can be carried by a CG                only if there is a corresponding PSFCH configuration for                the CG        -   For a TB with SL HARQ FB is disabled, up to RAN2 how to            utilize a CG for the transmission

Agreements:

-   -   For dynamic grant, DCI contains HARQ ID and NDI.

Agreements:

-   -   For dynamic grant, DCI indicates the time-frequency resource        allocation with the signalling format used for SCI.        -   In addition, the starting sub-channel for initial            transmission is signalled in DCI.

Agreements:

-   -   To provide additional resources for retransmission upon        receiving a SL NACK report, a dynamic grant is used.        -   When the initial transmission of a TB is scheduled by a            dynamic grant, the CRC of the DCI carrying the dynamic grant            is scrambled using the SL RNTI introduced for DCI for a            dynamic grant.            -   The interpretation of NDI is the same as for Uu for                retransmission scheduled by DCI with CRC scrambled by                C-RNTI        -   When the initial transmission of a TB is scheduled by a            configured grant (type-1 or type-2), the CRC of the DCI            carrying the dynamic grant is scrambled using the SL RNTI            introduced for DCI for a configured grant type-2.            -   For interpretation of NDI, the Uu behavior for                retransmission scheduled by DCI with CRC scrambled by                CS-RNTI is reused.        -   (working assumption) The HARQ ID is used to identify the TB            for which resources for retransmission are provided (subject            to the indication of re-transmission via NDI)

Agreements:

-   -   For dynamic grant, the number of retransmissions of a TB is up        to the gNB.    -   For configured grant, the maximum number of times that a TB can        be retransmitted using the resources provided by the configured        grant is configured per priority per configured grant.

Working assumption:

-   -   The timing of the PUCCH used for conveying SL HARQ is indicated        in DCI or RRC (only for transmissions without a DCI) in terms of        PSFCH-to-PUCCH physical slots, where the slot duration is        defined based on the PUCCH SCS.        -   Note: it is not intended to define any new sync requirements            for gNBs

Conclusion:

-   -   No support of multiplexing of SL HARQ and Uu UCI on PUCCH or        PUSCH in Rel-16        -   Note: this reverts the agreements made during RAN1#98b email            discussion

Agreements:

-   -   For dynamic grant and CG:        -   If the gNB provides PUCCH resources for feedback, the UE            reports SL HARQ FB to the gNB        -   If the gNB does not provides PUCCH resources for feedback,            the UE does not report SL HARQ FB to the gNB

Agreements:

-   -   For case of DG and type 2 CG: one combination of “timing and        resource for PUCCH” is used to indicate that PUCCH resource is        not provided    -   For type 1 CG: no RRC configuration of PUCCH resources indicates        that PUCCH resource is not provided

Agreements:

-   -   At least the following parameters are part of a SL configured        grant configuration:        -   Configuration index of the CG        -   Time offset (for type-1 only)        -   Time-frequency allocation (for type-1 only)            -   Using the same format as in DCI.        -   Periodicity        -   The configured grant is associated with a single transmit            resource pool.        -   RAN2 can add other parameters if deemed necessary by RAN2    -   A UE in mode 1 is configured at least with one transmit resource        pool    -   For type-2 CG, the time-frequency allocation and the        configuration index of the CG are indicated in DCI.        -   All parameters for CG type 2 for activation DCI re-use the            same respective parameters configured for CG type 1, when            applicable

Agreements:

-   -   NR supports SL transmissions at least in cell-specific UL        resources in Uu.

Agreements:

-   -   For signaling frequency resources of actual PSFCH transmission,        down select one of followings:        -   Bitmap indicates RBs in a resource pool

Agreements:

-   -   When a RX UE sends one bit HARQ-ACK in PSFCH        -   ACK and NACK are differentiated using different cyclic shift            of the same base sequence in the same PRB.        -   The cyclic shift corresponding to ACK is not defined/used            for groupcast option 1.

Agreements:

-   -   CDM between PSFCH transmissions from different UEs in the same        PRB is supported as follows:        -   Cyclic shift can be selected based on            -   the L1 source ID of TX UE for unicast and groupcast                option 1.            -   the L1 source ID of TX UE and the member ID of RX UE in                groupcast option 2.            -   FFS whether or not to use additional parameter(s) for                the selection (e.g., using PSCCH DM-RS, etc) 4 to                conclude this week        -   Base sequence is            -   (Pre-)configured per resource pool

Working assumption:

-   -   One PSFCH transmission can include up to X HARQ-ACK bits.        -   X=1

One or multiple of following terminologies may be used hereafter:

-   -   BS: A network central unit or a network node in NR which is used        to control one or multiple TRPs which are associated with one or        multiple cells. Communication between BS and TRP(s) is via        fronthaul. BS could also be referred to as central unit (CU),        eNB, gNB, or NodeB.    -   TRP: A transmission and reception point provides network        coverage and directly communicates with UEs. TRP could also be        referred to as distributed unit (DU) or network node.    -   Cell: A cell is composed of one or multiple associated TRPs,        i.e. coverage of the cell is composed of coverage of all        associated TRP(s). One cell is controlled by one BS. Cell could        also be referred to as TRP group (TRPG).    -   NR-PDCCH: A channel carries downlink control signal which is        used to control communication between a UE and a network side. A        network transmits NR-PDCCH on configured control resource set        (CORESET) to the UE.    -   Slot: A slot could be a scheduling unit in NR. A slot duration        has 14 OFDM symbols.    -   Mini-slot: A scheduling unit with duration less than 14 OFDM        symbols.    -   DL common signal: A data channel carrying common information        that targets for multiple UEs in a cell or all UEs in a cell.        Example of DL common signal could be system information, paging,        RAR.

One or multiple of following assumptions for network side may be usedhereafter:

-   -   Downlink timing of TRPs in the same cell are synchronized.    -   RRC layer of network side is in BS.

One or multiple of following assumptions for UE side may be usedhereafter:

-   -   There are at least two UE (RRC) states: connected state (or        called active state) and non-connected state (or called inactive        state or idle state). Inactive state may be an additional state        or belong to connected state or non-connected state.

For NR V2X transmission, there are two sidelink resource allocationmodes defined for NR-V2X sidelink communication (as discussed in 3GPPR1-1810051):

-   -   mode 1 is that base station/network node can schedule sidelink        resource(s) to be used by UE for sidelink transmission(s), which        concept is similar as sidelink transmission mode 3 in LTE/LTE-A        (as discussed in 3GPP TS 36.213);    -   mode 2 is that UE determines (i.e. base station/network node        does not schedule) sidelink transmission resource(s) within        sidelink resources configured by base station/network node or        pre-configured sidelink resources, which concept is similar as        sidelink transmission mode 4 in LTE/LTE-A (as discussed in 3GPP        TS 36.213).

For network scheduling mode, the network node may transmit a sidelink(SL) grant on Uu interface for scheduling resources of Physical SidelinkControl Channel (PSCCH) and/or Physical Sidelink Shared Channel (PSSCH).The V2X UE may perform PSCCH and PSSCH transmissions on PC5 interface,in response to the receive sidelink grant. The Uu interface means thewireless interface for communication between network and UE. The PC5interface means the wireless interface for communication (directly)between UEs or devices.

For UE (autonomous) selection mode, since transmission resource is notscheduled via network, the UE may require performing sensing beforeselecting a resource for transmission (e.g., sensing-basedtransmission), in order to avoid resource collision and interferencefrom or to other UEs. Based on the sensing procedure, the UE candetermine a valid resource set. The valid resource set may be reportedto higher layers (of the UE). The UE may select one or multiple validresources from the valid resource set to perform sidelinktransmission(s) from the UE. The transmission(s) from the UE may bePSCCH and/or PSSCH transmission.

Since NR V2X has requirement of high reliability and high throughputrequirement, it is considered to support SL HARQ feedback for unicastand/or groupcast. It could mean that a TX UE transmits a sidelink datatransmission to a RX UE, and then the RX UE may transmit SL (HybridAutomatic Request Request) HARQ feedback to the TX UE via (PhysicalSidelink Feedback Channel) PSFCH transmission.

If the SL HARQ feedback is Acknowledgement (ACK), it may mean the RX UEreceives and decodes the sidelink data transmission successfully. Whenthe TX UE receives the SL HARQ feedback as ACK, the TX UE may transmitanother new sidelink data transmission to the RX UE if there areavailable data from the TX UE to the RX UE.

If the SL HARQ feedback is NACK, it may mean the RX UE does not receiveand decode the sidelink data transmission successfully. When the TX UEreceives the SL HARQ feedback as Negative Acknowledgement (NACK), the TXUE may retransmit the sidelink data transmission to the RX UE.

Since the sidelink data retransmission carries the same data packet asthe sidelink data transmission, the RX UE may combine the sidelink datatransmission and sidelink data retransmission and then perform decodingfor the data packet. The combining can increase possibility of decodingsuccessfully.

In the RAN1 #96bis meeting (as discussed in 3GPP R1-1905921), it issupported that in a resource pool, PSFCH resources are (pre)configuredperiodically with a period of N slot(s), wherein N can be configured as1, 2, or 4 (as discussed in 3GPP R1-19059021 and R1-1907973). Moreover,the PSFCH periodicity configuration should also include the possibilityof no resource for PSFCH. In this case, HARQ feedback for alltransmissions in the resource pool is disabled (as discussed in 3GPPR1-1905921).

In network scheduling mode, since the sidelink resources are scheduledor assigned by network node, it is supported that the TX UE reports SLHARQ feedback via PUCCH to the network node. In one embodiment, the TXUE may deliver the SL HARQ feedback, received via PSFCH from the RX UE,to network node via PUCCH. When the network node receives the SL HARQfeedback from the TX UE, the network node can determine whether toschedule sidelink retransmission resource(s) to the TX UE.

For dynamic SL grant or type-2 configured SL grant, the timing andresource of the Physical Uplink Control Channel (PUCCH) used forconveying SL HARQ feedback are indicated in Downlink Control Information(DCI) (as discussed in 3GPP R1-1913275). In one embodiment, the DCIcould deliver the dynamic SL grant. The DCI could also deliveractivation of type-2 configured SL grant. Furthermore, the DCI coulddeliver the dynamic SL grant for providing sidelink retransmissionresource(s). In one embodiment, the sidelink retransmission resourcesmay be associated with an initial transmission of a Transport Block (TB)scheduled by a dynamic grant or a configured grant (type-1 or type-2).One combination of “timing and resource for PUCCH” in the DCI may beused to indicate that PUCCH resource is not provided (as discussed inthe Draft Report of 3GPP TSG RAN WG1 #99).

For type-1 configured SL grant, Radio Resource Control (RRC) is used toconfigure the timing and resource of the PUCCH (as discussed in 3GPPR1-1913275). If there is no RRC configuration of PUCCH resources, it maymean to indicate that PUCCH resource is not provided (as discussed inthe Draft Report of 3GPP TSG RAN WG1 #99).

Currently, for a UE configured in network scheduling mode, the networknode can provide resource pool configuration and provide PUCCH resourcefor reporting SL HARQ feedback. However, if the network node schedulessidelink resource(s) in a resource pool without PSFCH resources, and ifthe TX UE performs sidelink data transmission(s) in the sidelinkresource(s) in the resource pool, the TX UE cannot acquire SL HARQfeedback from RX UE. Thus, the TX UE may perform the sidelinktransmission(s) for delivering data with SL HARQ feedback disabled. Inthis case, if the network node provides PUCCH resource associated withthe sidelink resource(s), it is questionable how the TX UE reports SLHARQ feedback to the network node. To address this issue, there are somemethods/embodiments are discussed below:

Method a

A first device may receive a SL grant, wherein the SL grantschedules/indicates at least a sidelink resource. In one embodiment, theSL grant may indicate a PUCCH resource. The PUCCH resource may beassociated with the sidelink resource or the SL grant. In oneembodiment, the sidelink resource may be comprised within a sidelinkresource pool. The sidelink resource pool may be configured with noPSFCH resource.

Alternatively, there may be no PSFCH configuration for the sidelinkresource pool. The SL HARQ feedback could be disabled in the sidelinkresource pool. It (e.g. no PSFCH or SL HARQ feedback disable) may be dueto Channel Busy Ratio (CBR) of the sidelink resource pool being higherthan a threshold. Preferably or alternatively, it (e.g. no PSFCH or SLHARQ feedback disable) may be (pre-)configured for the sidelink resourcepool.

The first device may perform a sidelink transmission on the sidelinkresource to at least a second device. The sidelink transmission maycomprise, include, or deliver at least a data packet.

The general concept of Method a is that in this case, the first devicemay still report SL HARQ feedback via the PUCCH resource to networknode, even though the first device does not receive SL HARQ feedbackfrom at least the second device. In one embodiment, the first device maydetermine or derive how to report SL HARQ feedback. The first device mayreport SL HARQ feedback via the PUCCH resource after performing thesidelink transmission.

Embodiment 1

In one embodiment, the first device may (always) report SL HARQ feedbackas ACK. In other words, even though the first device does not receive SLHARQ feedback from at least the second device, the first device couldstill report SL HARQ feedback as ACK to the network node.

In this embodiment, the network node may not transmit another SL grantfor retransmission of the data packet. Alternatively, the network nodemay transmit another SL grant for retransmission of the data packet.Even though the network node cannot know whether the data packet isdelivered successfully to at least the second device, the network nodemay assume or determine a number of (re-)transmissions of the datapacket. In one embodiment, if network node knows that the sidelink(re-)transmission on the sidelink resource does not exceed the number,the network node can transmit another SL grant for retransmission of thedata packet. If network node knows that the sidelink (re-)transmissionon the sidelink resource is the last time retransmission of the datapacket, the network node may not transmit another SL grant forretransmission of the data packet.

In this embodiment, one aspect is that SL HARQ report from the firstdevice to the network node may be considered as confirmation that thefirst device receives the SL grant and utilize the scheduled/indicatedsidelink resource. The network node may be responsible to take care ofthe number of (re-)transmission of the data packet. Moreover, if thenetwork node does not receive or detect ACK via the PUCCH resource or ifthe network node does not detect any transmission via the PUCCH resource(e.g. DTX), the network node may transmit another SL grant forretransmission of the data packet.

Embodiment 2

In one embodiment, the first device may (always) report SL HARQ feedbackas NACK. In other words, even though the first device does not receiveSL HARQ feedback from at least the second device, the first device stillreports SL HARQ feedback as NACK to the network node.

In this embodiment, the network node may not transmit another SL grantfor retransmission of the data packet. Alternatively, the network nodemay transmit another SL grant for retransmission of the data packet.Even though the network node cannot know whether the data packet isdelivered successfully to at least the second device, the network nodemay assume or determine a number of (re-)transmissions of the datapacket. In one embodiment, if network node knows that the sidelink(re-)transmission on the sidelink resource does not exceed the number,the network node can transmit another SL grant for retransmission of thedata packet. If network node knows that the sidelink (re-)transmissionon the sidelink resource is the last time retransmission of the datapacket, the network node does not transmit another SL grant forretransmission of the data packet.

In this embodiment, one general aspect is that SL HARQ report from thefirst device to the network node may be considered as confirmation thatthe first device receives the SL grant and utilize the scheduled orindicated sidelink resource. The network node is responsible to takecare of the number of (re-)transmission of the data packet. Moreover, ifthe network node does not receive or detect NACK via the PUCCH resourceor if the network node does not detect any transmission via the PUCCHresource (e.g. DTX), the network node may transmit another SL grant forretransmission of the data packet.

Embodiment 3

In one embodiment, even though the first device does not receive SL HARQfeedback from at least the second device, the first device could(autonomously) determine or derive SL HARQ feedback for reporting to thenetwork node. In one embodiment, when the first device generates a datapacket, the first device may determine or derive a (maximum orallowable) number of times that the data packet can be (re-)transmitted.The first device may perform the sidelink transmission on the sidelinkresource, wherein the sidelink transmission delivers, includes, orcomprises the data packet. If the sidelink transmission on the sidelinkresource is the last time that the data packet can be (re-)transmitted,the first device could report SL HARQ feedback as ACK via the PUCCHresource. If the sidelink transmission on the sidelink resource is notthe last time that the data packet can be (re-)transmitted, the firstdevice could report SL HARQ feedback as NACK via the PUCCH resource. Inone embodiment, if the sidelink transmission on the sidelink resourcedoes not exceed the number of times that the data packet can be(re-)transmitted, and/or if the sidelink transmission is not the lasttime that the data packet can be (re-)transmitted, the first devicecould report SL HARQ feedback as NACK via the PUCCH resource.

In this embodiment, if network node receives or detects ACK via thePUCCH resource, the network node may not transmit another SL grant forretransmission of the data packet. If network node receives or detectsNACK via the PUCCH resource, the network node may transmit another SLgrant for retransmission of the data packet.

In one embodiment, the number of times may be derived based on priorityof the data packet. The number of times may also be derived based on alogical channel priority, wherein the data packet comprises databelonging to the logical channel. If the data packet comprises (only)Medium Access Control (MAC) Control Element (CE), the number of timesmay be associated with the MAC CE. If the data packet comprises databelonging to more than one logical channel (or MAC CE), the number oftimes may be derived base on the logical channel with highest prioritywithin the more than one logical channel (or based on the MAC CE).

Alternatively, if the data packet comprises data belonging to more thanone logical channel (or MAC CE), the number of times may be derived baseon the logical channel with largest number of times within the more thanone logical channel (or based on the MAC CE). Alternatively, if the datapacket comprises data belonging to more than one logical channel (or MACCE), wherein each logical channel may be associated with one number (orthe MAC CE is associated with one number), the number of times may bederived based on the largest number among the more than one numberassociated with the more than one logical channel (or the one numberassociated with the MAC CE).

In one embodiment, when the first device receives a SL grant schedulingat least a sidelink resource, the SL grant could indicate a PUCCHreporting timing (e.g. slot) by a time offset field. Based on theindicated time offset, the first device may derive a timing (e.g. slot)to transmit the PUCCH delivering SL HARQ feedback associated to thesidelink resource or the SL grant. The SL grant could provide a (validor available) PUCCH resource for reporting SL HARQ feedback to thenetwork node.

In one embodiment, if the sidelink resource pool is (pre-)configuredwith PSFCH resource, the first device may consider that the time offsetis from PSFCH to PUCCH, i.e. PSFCH to PUCCH. If the sidelink resourcepool is (pre-)configured with no PSFCH resource, the first device mayconsider that the time offset is replaced from “PSFCH to PUCCH” to“PSSCH or PSCCH to PUCCH” or “PDCCH to PUCCH”. In one embodiment, PSSCHor PSCCH may be the channel and/or the sidelink resource scheduled bythe SL grant. PDCCH could be the channel delivering the SL grant. In oneembodiment, the time offset could be by counting from physical slots.The counting slot could be determined based on uplink slot numerology orsubcarrier spacing (SCS).

Method b

The general concept of Method b is for network node to restrict somecombination of configurations. In one embodiment, the network node maytransmit, deliver, configure, or schedule a SL grant to a first device,wherein the SL grant schedules or indicates at least a sidelinkresource. The sidelink resource may be comprised within a sidelinkresource pool.

In one embodiment, if the sidelink resource pool is configured with noPSFCH resource, the network node shall not provide PUCCH resourceassociated with the sidelink resource or the SL grant. The network node(is restricted to) excludes, precludes, or prevents from providing aPUCCH resource associated with the sidelink resource or the SL grant.

Alternatively, if there is no PSFCH configuration for the sidelinkresource pool, the network node shall not provide PUCCH resourceassociated with the sidelink resource or the SL grant. The network node(is restricted to) excludes, precludes, or prevents from providing aPUCCH resource associated with the sidelink resource or the SL grant. Inother words, if the network node schedules, assigns, or configures thesidelink resource, to the first device, in a sidelink resource poolwithout PSFCH resources, the network node shall not provide PUCCHresource, for reporting SL HARQ, to the first device. The network node(is restricted to) excludes, precludes, or prevents from providing aPUCCH resource, for reporting SL HARQ, to the first device.

In one embodiment, the SL grant may only indicate or may only be allowedto indicate a combination or codepoint indicating no PUCCH resource.Accordingly, the first device could perform a sidelink transmission onthe sidelink resource to at least a second device, and the first devicemay not report SL HARQ feedback to the network node (after performingthe sidelink transmission) since the first device cannot acquire SL HARQfeedback from at least the second device.

From the perspective of the first device, if the first device receives aSL grant scheduling the sidelink resource in a sidelink resource poolwithout PSFCH resources, the first device may assume, expect, orconsider that the SL grant does not provide PUCCH resource for reportingSL HARQ feedback. The first device may not be expected or may not expectto receive the SL grant providing a PUCCH resource associated to thescheduled sidelink resource in a sidelink resource pool without PSFCHresource. The first device may not be expected or may not expect toreceive the SL grant providing a PUCCH resource and scheduling sidelinkresource in a sidelink resource pool without PSFCH resource.

In one embodiment, if the SL grant provides PUCCH resource for reportingSL HARQ feedback associated with a sidelink resource in a sidelinkresource pool without PSFCH resources, the first device may ignore thePUCCH-related field in the SL grant. If the SL grant schedules asidelink resource in a sidelink resource pool without PSFCH resourcesand the SL grant provides PUCCH resource for reporting SL HARQ feedbackassociated with the sidelink resource or the SL grant, the first devicemay ignore the PUCCH-related field in the SL grant.

Alternatively, if the SL grant provided PUCCH resource for reporting SLHARQ feedback associated with a sidelink resource in a sidelink resourcepool without PSFCH resources, the first device may consider the SL grantis an inconsistent scheduling and/or drop the SL grant. If the SL grantschedules a sidelink resource in a sidelink resource pool without PSFCHresources and the SL grant provides PUCCH resource for reporting SL HARQfeedback associated with the sidelink resource or the SL grant, thefirst device may consider the SL grant is an inconsistent schedulingand/or drop the SL grant. If the first device drops the SL grant, thefirst device may not perform sidelink transmission on the sidelinkresource scheduled by the SL grant.

In one embodiment, if a DCI delivers or schedules the SL grant, one(codepoint) combination or one codepoint of field(s) in the DCI may beused to indicate that PUCCH resource is not provided. Other combinationsor other codepoints of the field(s) may be used for indicating timing orresource for PUCCH. If RRC delivers or configure the SL grant, theconfiguration for the SL grant may not include PUCCH resourceconfiguration. The configuration for the SL grant may not indicatetiming and resource of PUCCH resource for reporting SL HARQ feedback. Itcould mean that PUCCH resource may not be provided for the SL grant.

For All Above Concepts, Methods, Alternatives and Embodiments

Any of above methods, alternatives and embodiments may be combined orapplied simultaneously.

In one embodiment, the SL grant may be a dynamic SL grant. The timingand resource of PUCCH resource used for reporting SL HARQ feedback maybe indicated, scheduled, or assigned in a DCI (downlink controlinformation). One (codepoint) combination or one codepoint of field(s)in the DCI may be used to indicate that PUCCH resource is not provided.Other combinations or other codepoints of the field(s) may be used forindicating timing and/or resource for PUCCH.

In one embodiment, the DCI could deliver a dynamic SL grant. The DCIcould be scrambled using SL RNTI introduced for DCI for a dynamic SLgrant. The DCI could deliver a dynamic SL grant for providing sidelinkretransmission resource(s), which is associated with an initialtransmission of a TB scheduled by a dynamic SL grant. The DCI could bescrambled using SL RNTI introduced for DCI for a dynamic SL grant. Inone embodiment, the DCI could deliver a dynamic SL grant for providingsidelink retransmission resource(s), which is associated with an initialtransmission of a TB scheduled by a (type-1 or type-2) configured SLgrant. The DCI could be scrambled using SL Radio Network TemporaryIdentifier (RNTI) introduced for DCI for a type-2 configured SL grant.

In one embodiment, the SL grant may be a type-2 configured SL grant. Thetiming and resource of PUCCH resource used for reporting SL HARQfeedback may be indicated, scheduled or assigned in a DCI. One(codepoint) combination or one codepoint of field(s) in the DCI may beused to indicate that PUCCH resource is not provided. Other combinationsor other codepoints of the field(s) may be used for indicating timing orresource for PUCCH.

In one embodiment, the DCI could deliver the activation of the type-2configured SL grant. The DCI could be scrambled using SL RNTI introducedfor DCI for a type-2configured SL grant.

In one embodiment, the DCI could deliver a dynamic SL grant forproviding sidelink retransmission resource(s), which is associated withan initial transmission of a TB scheduled by the type-2 configured SLgrant. The DCI could be scrambled using SL RNTI introduced for DCI for atype-2configured SL grant.

In one embodiment, the SL grant may be a type-1 configured SL grant. Thetiming and resource of PUCCH resource used for reporting SL HARQfeedback could be indicated or configured in RRC signaling. If theconfiguration for the type-1 configured SL grant does not include PUCCHresource configuration, PUCCH resource may not be provided for thetype-1 configured SL grant. If the configuration for the type-1configured SL grant does not indicate timing and resource of PUCCHresource for reporting SL HARQ feedback, PUCCH resource may not beprovided for the type-1 configured SL grant.

In one embodiment, the another SL grant could indicate a same HARQ ID asthe SL grant. The another SL grant could also indicate a non-toggled NDIvalue as the SL grant. The another SL grant could be scrambled using SLRNTI introduced for DCI for a dynamic SL grant.

In one embodiment, the another SL grant could indicate a NDI value as 1.The another SL grant could be scrambled using the SL RNTI introduced forDCI for a type-2configured SL grant.

In one embodiment, the first device may have, maintain, or establish asidelink link or connection with the second device. The more than onesidelink logical channel may be associated with the second device orassociated with the sidelink link or connection.

In one embodiment, the sidelink resource may be utilized for sidelinktransmission, reception, or communication of the sidelink link orconnection. The sidelink link or connection may be a unicast link orconnection. The second device could be the paired device of the firstdevice. The sidelink link or connection may also be a groupcast link orconnection. The first device and the second device may be within a samesidelink group. The sidelink link or connection may be a broadcast linkor connection. The second device may be a neighboring device around thefirst device.

In one embodiment, the first device may perform sidelink transmission,reception, or communication of the sidelink link or connection in thesidelink resource pool. The first device may also perform sidelinktransmission, reception, or communication of the sidelink link orconnection associated with network scheduling mode (e.g. NR SL mode 1).

In one embodiment, the network node may be a gNB, a base station, or aRoadside Unit (RSU) (i.e., a network-type RSU or a UE-type RSU). Thenetwork node may be replaced or represented by a specific device withina sidelink group.

In one embodiment, the logical channel may mean sidelink logicalchannel. The data comprised in the data packet may come from at least asidelink logical channel. The MAC CE comprised in the data packet couldbe utilized for the sidelink link or connection.

In one embodiment, the data packet could be a sidelink data packet. Thedata packet may comprise data belonging to sidelink logical channel. Thedata packet may comprise sidelink MAC CE. The data packet may notcomprise data belonging to Uu-interface logical channel. The data packetmay not comprise Uu-interface MAC CE.

In one embodiment, the sidelink transmission may be PSSCH or PSCCH.

In one embodiment, the sidelink slot may mean slot for sidelink. Asidelink slot may be represented as a Transmission Time Interval (TTI).A TTI may be a subframe (for sidelink). A TTI may comprise multiplesymbols, e.g. 12 or 14 symbols. The TTI may be a slot (fully/partially)comprising sidelink symbols. The TTI may mean a transmission timeinterval for a sidelink (data) transmission.

In one embodiment, a sidelink slot or a slot for sidelink may containall Orthogonal Frequency Division Multiplexing (OFDM) symbols availablefor sidelink transmission. A sidelink slot or a slot for sidelink maycontain a consecutive number symbols available for sidelinktransmission. A sidelink slot or a slot for sidelink may mean that aslot is included in a sidelink resource pool. The symbol may mean asymbol indicated or configured for sidelink.

In one embodiment, a sub-channel may be a unit for sidelink resourceallocation or scheduling (for PSSCH). A sub-channel may comprisemultiple contagious PRBs in frequency domain. The number of PRBs foreach sub-channel may be (pre-)configured for a sidelink resource pool. Asidelink resource pool (pre-)configuration may indicate or configure thenumber of PRBs for each sub-channel. The number of PRBs for eachsub-channel may be any of 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 25, 30,48, 50, 72, 75, 96, or 100.

In one embodiment, a sub-channel may be represented as a unit forsidelink resource allocation or scheduling. A sub-channel may mean aPRB. A sub-channel may mean a set of consecutive PRBs in frequencydomain. A sub-channel may mean a set of consecutive resource elements infrequency domain.

In one embodiment, the SL HARQ feedback may comprise ACK or NACK. The SLHARQ feedback for a data packet from the second device to the firstdevice may be derived based on whether the second device successfullyreceives or decodes the data packet delivered in the associated sidelink(re)transmission from the first device.

In one embodiment, a data packet may mean a TB. A data packet may mean aMAC PDU. A data packet may mean one or two TB(s) delivered or includedin one sidelink (re)transmission.

In one embodiment, the sidelink transmission or reception may bedevice-to-device transmission or reception, V2X transmission orreception, or P2X transmission or reception. The sidelink transmissionor reception may be on PC5 interface.

In one embodiment, the PC5 interface may be wireless interface forcommunication between device and device. The PC5 interface may bewireless interface for communication between devices. The PC5 interfacemay be wireless interface for communication between UEs. The PC5interface may be wireless interface for V2X or P2X communication.

In one embodiment, the Uu interface may be wireless interface forcommunication between network node and device. The Uu interface may bewireless interface for communication between network node and UE.

In one embodiment, the first device and the second device are differentdevices. The first device may be a UE, a vehicle UE, a V2X UE, or atransmitting UE.

In one embodiment, the second device may be a UE. In particular, thesecond device may be a vehicle UE, a V2X UE, or a receiving UE.

In one embodiment, PUCCH could be replaced by PUSCH (when the firstdevice receives an uplink grant scheduling the PUSCH on the same slot asthe PUCCH). In this case, the first device may report SL HARQ feedbackvia the PUSCH resource in the same slot, instead of via the PUCCHresource.

FIG. 9 is a flow chart 900 according to one exemplary embodiment fromthe perspective of a network node to schedule sidelink resources. Instep 905, the network node configures a first sidelink resource poolwithout any PSFCH resource. In step 910, the network node transmits,configures, or schedules a first sidelink grant to a first device,wherein the first sidelink grant schedules or indicates at least a firstsidelink resource in the first sidelink resource pool. In step 915, thenetwork excludes, precludes, or prevents from providing a PUCCH resourceassociated with the first sidelink resource or the first sidelink grant.

In one embodiment, the first sidelink grant may be transmitted orscheduled via a DCI, wherein one (codepoint) combination or onecodepoint of field(s) in the DCI is set to indicate that PUCCH resourceis not provided, and/or the first sidelink grant may only indicate ormay be only allowed to indicate the one combination or the one codepointof field(s) indicating that PUCCH resource is not provided. Furthermore,the first sidelink grant could be transmitted or configured via RRCsignaling, wherein the configuration for the first sidelink grant doesnot include or provide PUCCH resource configuration.

In one embodiment, the network node could configure a second sidelinkresource pool with PSFCH resource. Furthermore, the network node couldtransmit, configure, or schedule a second sidelink grant to a seconddevice, wherein the second sidelink grant schedules or indicates atleast a second sidelink resource in the second sidelink resource pool.In addition, the network node could be allowed to provide a PUCCHresource associated with the second sidelink resource or the secondsidelink grant. In one embodiment, the PUCCH resource is for the firstdevice to report SL HARQ feedback associated with corresponding sidelinkresource or corresponding sidelink grant.

Referring back to FIGS. 3 and 4, in one exemplary embodiment of anetwork node to schedule sidelink resources. The network node 300includes a program code 312 stored in the memory 310. The CPU 308 couldexecute program code 312 to enable the network node (i) to configure afirst sidelink resource pool without any PSFCH resource, (ii) totransmit, configure, or schedule a first sidelink grant to a firstdevice, wherein the first sidelink grant schedules or indicates at leasta first sidelink resource in the first sidelink resource pool, and (iii)to exclude, preclude, or prevent from providing a PUCCH resourceassociated with the first sidelink resource or the first sidelink grant.Furthermore, the CPU 308 can execute the program code 312 to perform allof the above-described actions and steps or others described herein.

FIG. 10 is a flow chart 1000 according to one exemplary embodiment fromthe perspective of a first device. In step 1005, the first devicereceives a configuration, from a network node, of a first sidelinkresource pool without any PSFCH resource. In step 1010, the first devicereceives a first sidelink grant transmitted, configured, or scheduled bythe network node, wherein the first sidelink grant schedules orindicates at least a first sidelink resource in the first sidelinkresource pool. In step 1015, the first device expects or considers thatthe first sidelink grant provides no PUCCH resource for reporting SLHARQ feedback.

In one embodiment, the first sidelink grant could be transmitted orscheduled via a DCI, wherein one (codepoint) combination or onecodepoint of field(s) in the DCI is set to indicate that PUCCH resourceis not provided, and/or the first sidelink grant could only indicate orcould be only allowed to indicate the one combination or the onecodepoint of field(s) indicating that PUCCH resource is not provided.

In one embodiment, the first sidelink grant could be transmitted orconfigured via RRC signaling, wherein the configuration for the firstsidelink grant does not include or provide PUCCH resource configuration.If the first sidelink grant provided PUCCH resource for reporting SLHARQ feedback associated with the first sidelink resource or the firstsidelink grant, the first device could consider the first sidelink grantis an inconsistent scheduling and/or drop the first sidelink grant. Ifthe first device drops the first sidelink grant, the first device maynot perform sidelink transmission on the first sidelink resourcescheduled by the first sidelink grant.

Referring back to FIGS. 3 and 4, in one exemplary embodiment of a firstdevice. The first device 300 includes a program code 312 stored in thememory 310. The CPU 308 could execute program code 312 to enable thefirst device (i) to receive a configuration, from a network node, of afirst sidelink resource pool without any PSFCH resource, (ii) to receivea first sidelink grant transmitted, configured, or scheduled by thenetwork node, wherein the first sidelink grant schedules or indicates atleast a first sidelink resource in the first sidelink resource pool, and(iii) to expect or consider that the first sidelink grant provides noPUCCH resource for reporting SL HARQ feedback. Furthermore, the CPU 308can execute the program code 312 to perform all of the above-describedactions and steps or others described herein.

FIG. 11 is a flow chart 1100 according to one exemplary embodiment fromthe perspective of a first device to perform sidelink communication. Instep 1105, the first device operates sidelink communication in a carrieror cell, wherein the carrier or cell comprises a sidelink resource poolwithout PSFCH resource. In step 1110, the first device receives a SLgrant, wherein the SL grant schedules or indicates at least a sidelinkresource in the sidelink resource pool, and the SL grant indicates aPUCCH resource. In step 1115, the first device performs a sidelinktransmission on the sidelink resource to at least a second device,wherein the sidelink transmission comprises, includes, or delivers atleast a data packet. In step 1120, the first device reports a feedbackvia the PUCCH resource after performing the sidelink transmission.

In one embodiment, the PUCCH resource could be associated with thesidelink resource or the SL grant. The first device may not receive SLHARQ feedback from at least the second device. The first device may(always) report the feedback as ACK. Alternatively, the first device may(always) report the feedback as NACK.

In one embodiment, the first device could determine or derive a (maximumor allowable) number of times that the data packet can be(re-)transmitted. If the sidelink transmission on the sidelink resourceis the last time that the data packet can be (re-)transmitted, the firstdevice could report SL HARQ feedback as ACK via the PUCCH resource. Ifthe sidelink transmission on the sidelink resource is not the last timethat the data packet can be (re-) transmitted, the first device couldreport SL HARQ feedback as NACK via the PUCCH resource.

In one embodiment, the number of times could be derived based on asidelink logical channel priority, wherein the data packet comprisesdata belonging to the sidelink logical channel. If the data packetcomprises (only) MAC CE, the number of times could be associated withthe MAC CE.

Referring back to FIGS. 3 and 4, in one exemplary embodiment of a firstdevice to perform sidelink communication. The first device 300 includesa program code 312 stored in the memory 310. The CPU 308 could executeprogram code 312 to enable the first device (i) to operate sidelinkcommunication in a carrier or cell, wherein the carrier or cellcomprises a sidelink resource pool without PSFCH resource, (ii) toreceive a SL grant, wherein the SL grant schedules or indicates at leasta sidelink resource in the sidelink resource pool, and the SL grantindicates a PUCCH resource, (iii) to perform a sidelink transmission onthe sidelink resource to at least a second device, wherein the sidelinktransmission comprises, includes, or delivers at least a data packet,and (iv) to report a feedback via the PUCCH resource after performingthe sidelink transmission. Furthermore, the CPU 308 can execute theprogram code 312 to perform all of the above-described actions and stepsor others described herein.

Various aspects of the disclosure have been described above. It shouldbe apparent that the teachings herein may be embodied in a wide varietyof forms and that any specific structure, function, or both beingdisclosed herein is merely representative. Based on the teachings hereinone skilled in the art should appreciate that an aspect disclosed hereinmay be implemented independently of any other aspects and that two ormore of these aspects may be combined in various ways. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, such an apparatusmay be implemented or such a method may be practiced using otherstructure, functionality, or structure and functionality in addition toor other than one or more of the aspects set forth herein. As an exampleof some of the above concepts, in some aspects concurrent channels maybe established based on pulse repetition frequencies. In some aspectsconcurrent channels may be established based on pulse position oroffsets. In some aspects concurrent channels may be established based ontime hopping sequences. In some aspects concurrent channels may beestablished based on pulse repetition frequencies, pulse positions oroffsets, and time hopping sequences.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, processors, means, circuits, and algorithmsteps described in connection with the aspects disclosed herein may beimplemented as electronic hardware (e.g., a digital implementation, ananalog implementation, or a combination of the two, which may bedesigned using source coding or some other technique), various forms ofprogram or design code incorporating instructions (which may be referredto herein, for convenience, as “software” or a “software module”), orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

In addition, the various illustrative logical blocks, modules, andcircuits described in connection with the aspects disclosed herein maybe implemented within or performed by an integrated circuit (“IC”), anaccess terminal, or an access point. The IC may comprise a generalpurpose processor, a digital signal processor (DSP), an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA) or other programmable logic device, discrete gate or transistorlogic, discrete hardware components, electrical components, opticalcomponents, mechanical components, or any combination thereof designedto perform the functions described herein, and may execute codes orinstructions that reside within the IC, outside of the IC, or both. Ageneral purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

It is understood that any specific order or hierarchy of steps in anydisclosed process is an example of a sample approach. Based upon designpreferences, it is understood that the specific order or hierarchy ofsteps in the processes may be rearranged while remaining within thescope of the present disclosure. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

The steps of a method or algorithm described in connection with theaspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module (e.g., including executable instructions and relateddata) and other data may reside in a data memory such as RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a harddisk, a removable disk, a CD-ROM, or any other form of computer-readablestorage medium known in the art. A sample storage medium may be coupledto a machine such as, for example, a computer/processor (which may bereferred to herein, for convenience, as a “processor”) such theprocessor can read information (e.g., code) from and write informationto the storage medium. A sample storage medium may be integral to theprocessor. The processor and the storage medium may reside in an ASIC.The ASIC may reside in user equipment. In the alternative, the processorand the storage medium may reside as discrete components in userequipment. Moreover, in some aspects any suitable computer-programproduct may comprise a computer-readable medium comprising codesrelating to one or more of the aspects of the disclosure. In someaspects a computer program product may comprise packaging materials.

While the invention has been described in connection with variousaspects, it will be understood that the invention is capable of furthermodifications. This application is intended to cover any variations,uses or adaptation of the invention following, in general, theprinciples of the invention, and including such departures from thepresent disclosure as come within the known and customary practicewithin the art to which the invention pertains.

The invention claimed is:
 1. A method of a network node to schedule NewRadio (NR) sidelink resources, comprising: the network node configures afirst NR sidelink resource pool, wherein the first NR sidelink resourcepool is configured with no Physical Sidelink Feedback Channel (PSFCH)resource, and wherein PSFCH resource is used for transmitting sidelinkHARQ feedback between devices; the network node transmits, configures,or schedules a first sidelink grant to a first device, wherein the firstsidelink grant schedules or indicates at least a first NR sidelinkresource in the first NR sidelink resource pool; and the networkexcludes, precludes, or prevents, based on the first NR sidelinkresource pool being configured with no PSFCH resource, from providing aPhysical Uplink Control Channel (PUCCH) resource associated with thefirst NR sidelink resource or the first sidelink grant.
 2. The method ofclaim 1, wherein the first sidelink grant is transmitted or scheduledvia a Downlink Control Information (DCI), wherein one combination or onecodepoint of field(s) in the DCI is set to indicate that PUCCH resourceis not provided, and/or the first sidelink grant only indicates or isonly allowed to indicate the one combination or the one codepoint offield(s) indicating that PUCCH resource is not provided.
 3. The methodof claim 1, wherein the first sidelink grant is transmitted orconfigured via Radio Resource Control (RRC) signaling, wherein theconfiguration for the first sidelink grant does not include or providePUCCH resource configuration.
 4. The method of claim 1, furthercomprising: the network node configures a second NR sidelink resourcepool with PSFCH resource; the network node transmits, configures, orschedules a second sidelink grant to a second device, wherein the secondsidelink grant schedules or indicates at least a second NR sidelinkresource in the second NR sidelink resource pool; and the network nodeis allowed to provide a PUCCH resource associated with the second NRsidelink resource or the second sidelink grant.
 5. The method of claim1, wherein the first NR sidelink resource pool, without any PSFCHresources, includes a PSFCH periodicity configuration of the first NRsidelink resource pool that indicates no resources for PSFCH.
 6. Anetwork node to schedule New Radio (NR) sidelink resources, comprising:a processor; and a memory operatively coupled to the processor, whereinthe processor is configured to execute a program code to: configure afirst NR sidelink resource pool, wherein the first NR sidelink resourcepool is configured with no Physical Sidelink Feedback Channel (PSFCH)resource, and wherein PSFCH resource is used for transmitting sidelinkHARQ feedback between devices; transmit, configure, or schedule a firstsidelink grant to a first device, wherein the first sidelink grantschedules or indicates at least a first NR sidelink resource in thefirst NR sidelink resource pool; and exclude, preclude, or prevent,based on the first NR sidelink resource pool being configured with noPSFCH resource, from providing a Physical Uplink Control Channel (PUCCH)resource associated with the first NR sidelink resource or the firstsidelink grant.
 7. The network node of claim 6, wherein the firstsidelink grant is transmitted or scheduled via a Downlink ControlInformation (DCI), wherein one combination or one codepoint of field(s)in the DCI is set to indicate that PUCCH resource is not provided,and/or the first sidelink grant only indicates or is only allowed toindicate the one combination or the one codepoint of field(s) indicatingthat PUCCH resource is not provided.
 8. The network node of claim 6,wherein the first sidelink grant is transmitted or configured via RadioResource Control (RRC) signaling, wherein the configuration for thefirst sidelink grant does not include or provide PUCCH resourceconfiguration.
 9. The network node of claim 6, wherein the processor isfurther configured to execute a program code stored in the memory to:configure a second NR sidelink resource pool with PSFCH resource;transmit, configure, or schedule a second sidelink grant to a seconddevice, wherein the second sidelink grant schedules or indicates atleast a second NR sidelink resource in the second sidelink NR resourcepool; and be allowed to provide a PUCCH resource associated with thesecond NR sidelink resource or the second sidelink grant.
 10. A methodof a first device, comprising: the first device receives aconfiguration, from a network node, of a first New Radio (NR) sidelinkresource pool, wherein the first NR sidelink resource pool is configuredwith no Physical Sidelink Feedback Channel (PSFCH) resource, and whereinPSFCH resource is used for transmitting sidelink HARQ feedback betweendevices; the first device receives a first sidelink grant transmitted,configured, or scheduled by the network node, wherein the first sidelinkgrant schedules or indicates at least a first NR sidelink resource inthe first sidelink NR resource pool; and the first device expects orconsiders, based on the first NR sidelink resource pool being configuredwith no PSFCH resource, that the first sidelink grant provides noPhysical Uplink Control Channel (PUCCH) resource for reporting Sidelink(SL) Hybrid Automatic Repeat Request (HARQ) feedback to the networknode.
 11. The method of claim 10, wherein the first sidelink grant istransmitted or scheduled via a Downlink Control Information (DCI),wherein one combination or one codepoint of field(s) in the DCI is setto indicate that PUCCH resource is not provided, and/or the firstsidelink grant only indicates or is only allowed to indicate the onecombination or the one codepoint of field(s) indicating that PUCCHresource is not provided.
 12. The method of claim 10, wherein the firstsidelink grant is transmitted or configured via Radio Resource Control(RRC) signaling, wherein the configuration for the first sidelink grantdoes not include or provide PUCCH resource configuration.
 13. The methodof claim 10, wherein if the first sidelink grant provided PUCCH resourcefor reporting SL HARQ feedback associated with the first NR sidelinkresource or the first sidelink grant, the first device considers thefirst sidelink grant is an inconsistent scheduling and/or drop the firstsidelink grant.
 14. The method of claim 13, wherein if the first devicedrops the first sidelink grant, the first device does not performsidelink transmission on the first NR sidelink resource scheduled by thefirst sidelink grant.
 15. The method of claim 10, wherein theconfiguration of the first NR sidelink resource pool, without any PSFCHresources, includes a PSFCH periodicity configuration of the first NRsidelink resource pool that indicates no resources for PSFCH.
 16. Afirst device, comprising: a processor; and a memory operatively coupledto the processor, wherein the processor is configured to execute aprogram code to: receive a configuration, from a network node, of afirst New Radio (NR) sidelink resource pool, wherein the first NRsidelink resource pool is configured with no Physical Sidelink FeedbackChannel (PSFCH) resource, and wherein PSFCH resource is used fortransmitting sidelink HARQ feedback between devices; receive a firstsidelink grant transmitted, configured, or scheduled by the networknode, wherein the first sidelink grant schedules or indicates at least afirst NR sidelink resource in the first NR sidelink resource pool; andexpect or consider, based on the first NR sidelink resource pool beingconfigured with no PSFCH resource, that the first sidelink grantprovides no Physical Uplink Control Channel (PUCCH) resource forreporting Sidelink (SL) Hybrid Automatic Repeat Request (HARQ) feedbackto the network node.
 17. The first device of claim 16, wherein the firstsidelink grant is transmitted or scheduled via a Downlink ControlInformation (DCI), wherein one combination or one codepoint of field(s)in the DCI is set to indicate that PUCCH resource is not provided,and/or the first sidelink grant only indicates or is only allowed toindicate the one combination or the one codepoint of field(s) indicatingthat PUCCH resource is not provided.
 18. The first device of claim 16,wherein the first sidelink grant is transmitted or configured via RadioResource Control (RRC) signaling, wherein the configuration for thefirst sidelink grant does not include or provide PUCCH resourceconfiguration.
 19. The first device of claim 16, wherein if the firstsidelink grant provided PUCCH resource for reporting SL HARQ feedbackassociated with the first NR sidelink resource or the first sidelinkgrant, the first device considers the first sidelink grant is aninconsistent scheduling and/or drop the first sidelink grant.
 20. Thefirst device of claim 19, wherein if the first device drops the firstsidelink grant, the first device does not perform sidelink transmissionon the first NR sidelink resource scheduled by the first sidelink grant.